C++字符串如何处理 string类常用方法

<blockquote>std::String相比C风格字符串具有内存自动管理、丰富API、操作符重载、边界安全检查和RaiI特性等优势，显著提升代码安全性与可读性；其核心方法如find、replace、reserve及c++17的string_view进一步优化了查找、替换与性能表现，适用于绝大多数现代C++场景。</blockquote> <p><img src=”https://img.php.cn/upload/article/000/969/633/175565592880903.png” alt=”c++字符串如何处理 string类常用方法”></p> <p>C++中处理字符串，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>无疑是现代C++的首选，它彻底改变了我们与文本数据交互的方式，提供了一套强大、安全且直观的接口，让开发者摆脱了C风格字符数组管理的诸多烦恼。说白了，它让字符串操作变得像操作普通对象一样自然。</p> <h3>解决方案</h3> <p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>类封装了字符串操作的复杂性，提供了丰富的方法来创建、修改、查找、比较和管理字符串。我个人觉得，理解并熟练运用这些方法，是写出高效、健壮C++代码的关键一步。</p> <ul> <li> <p><strong>创建与初始化：</strong><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>的构造函数非常灵活。你可以直接用字符串字面量初始化，也可以从另一个<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象、C风格字符串、甚至部分字符数组来构建。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>std::string s1 = "Hello, World!"; // 最常用 std::string s2("Another String"); std::string s3(s1); // 拷贝构造 std::string s4(5, ‘A’); // "AAAAA"</pre><div class=”contentsignin”></div></div><p>这比c语言里得先<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>malloc</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>再<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strcpy</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>，或者定义一个固定大小的数组，要省心太多了。</p> <p><span>立即学习</span>“<a href=”https://pan.quark.cn/s/6e7abc4abb9f” style=”text-decoration: underline !important; color: blue; font-weight: bolder;” rel=”nofollow” target=”_blank”>C++免费学习笔记（深入）</a>”；</p> </li> <li> <p><strong>访问与遍历：</strong> 你可以像访问数组一样使用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>[]</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>操作符来访问单个字符，或者用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>at()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>方法（它会进行边界检查，越界会抛出<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::out_of_range</pre><div class=”contentsignin”></div></div>异常，更安全）。同时，它也支持迭代器，可以方便地进行范围for循环遍历。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>std::string myStr = "C++"; char c = myStr[0]; // ‘C’ char c_safe = myStr.at(1); // ‘++’ // 遍历 for (char ch : myStr) { // 处理每个字符 }</pre><div class=”contentsignin”></div></div><p>在我看来，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>at()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>虽然多了一层检查开销，但在不确定索引是否越界时，它的安全性远比直接<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>[]</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>来得重要，尤其是在处理用户输入或外部数据时。</p> </li> <li> <p><strong>长度与容量：</strong><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>size()</pre><div class=”contentsignin”></div></div>和<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>Length()</pre><div class=”contentsignin”></div></div>方法都返回字符串的字符数（不包括空终止符），它们是等价的。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>empty()</pre><div class=”contentsignin”></div></div>判断字符串是否为空。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>capacity()</pre><div class=”contentsignin”></div></div>返回当前字符串可以容纳的字符数，不重新分配内存。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>reserve()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>可以预留内存，避免后续频繁的内存重新分配。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>std::string text = "example"; size_t len = text.length(); // 7 bool isEmpty = text.empty(); // false text.reserve(100); // 预留100字符空间</pre><div class=”contentsignin”></div></div><p>这个<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>reserve()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>方法在大量字符串拼接的场景下尤其重要，能显著提升性能。</p> </li> <li> <p><strong>连接与修改：</strong> 字符串连接可以通过<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>+</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>或<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>+=</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>操作符实现，也可以使用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>append()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>方法。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>push_back()</pre><div class=”contentsignin”></div></div>用于在末尾添加单个字符，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pop_back()</pre><div class=”contentsignin”></div></div>（C++11）则移除最后一个字符。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>insert()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>和<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>erase()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>则提供了在指定位置插入或删除字符序列的能力。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>clear()</pre><div class=”contentsignin”></div></div>清空字符串。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>std::string s = "Hello"; s += " World"; // "Hello World" s.append("!"); // "Hello World!" s.insert(6, "Big "); // "Hello Big World!" s.erase(0, 6); // "Big World!" s.push_back(‘?’); // "Big World!?" s.clear(); // ""</pre><div class=”contentsignin”></div></div><p>这些操作符和方法的重载非常丰富，可以满足几乎所有字符串修改的需求，比C语言里那些需要手动计算长度、移动内存的函数要优雅得多。</p> </li> <li> <p><strong>查找与提取：</strong><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>find()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>方法用于查找子字符串或字符的第一次出现位置，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>rfind()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>则查找最后一次出现位置。如果找不到，它们都返回<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string::npos</pre><div class=”contentsignin”></div></div>。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>substr()</pre><div class=”contentsignin”></div></div>方法可以提取子字符串。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>std::string sentence = "The quick brown fox jumps over the lazy dog."; size_t pos = sentence.find("fox"); // 16 if (pos != std::string::npos) { std::string sub = sentence.substr(pos, 3); // "fox" }</pre><div class=”contentsignin”></div></div><p>这里要特别注意<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>npos</pre><div class=”contentsignin”></div></div>的判断，这是个新手常常忽略的坑，不判断就直接用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pos</pre><div class=”contentsignin”></div></div>可能会导致运行时错误。</p> </li> <li> <p><strong>比较：</strong><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>支持所有标准的比较运算符（<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>==</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>, <div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>!=</pre><div class=”contentsignin”></div></div>, <div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”><</pre><div class=”contentsignin”></div></div>, <div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>></pre><div class=”contentsignin”></div></div>, <div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”><=</pre><div class=”contentsignin”></div></div>, <div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>>=</pre><div class=”contentsignin”></div></div>），它们会按字典序进行比较。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>compare()</pre><div class=”contentsignin”></div></div>方法则提供更细粒度的比较，可以指定比较的范围。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>std::string s_a = “apple”; std::string s_b = “banana”; if (s_a < s_b) { // true // … } int cmp = s_a.compare(s_b); // 负值表示s_a小于s_b</pre><div class=”contentsignin”></div></div></li> <li> <p><strong>C风格字符串交互：</strong><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>c_str()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>方法返回一个指向C风格字符串（以空字符<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”></pre><div class=”contentsignin”></div></div>结尾的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>const char*</pre><div class=”contentsignin”></div></div>）的指针。这在需要与C API或某些只接受C风格字符串的库函数交互时非常有用。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>data()</pre><div class=”contentsignin”></div></div>方法类似，但在C++11及以后版本，它返回的字符串不保证以空字符结尾，如果需要C风格兼容，还是用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>c_str()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>std::string greeting = "Hello"; const char* c_str_ptr = greeting.c_str(); // 可以传递给printf等C函数 // printf("%sn", c_str_ptr);</pre><div class=”contentsignin”></div></div><p>记住，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>c_str()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>返回的指针的生命周期与<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象绑定，一旦<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象被修改或销毁，该指针就可能失效。</p> </li> </ul> <h3><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>与C风格字符串相比，优势体现在哪里？</h3> <p>这真是一个老生常谈但又不得不提的问题。在我看来，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>相对于C风格字符串（<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>char*</pre><div class=”contentsignin”></div></div>或<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>char[]</pre><div class=”contentsignin”></div></div>）的优势是全方位的，它不仅仅是语法上的便利，更是工程实践中健壮性和安全性的巨大提升。</p> <p>首先，最核心的优势在于<strong>内存管理</strong>。C风格字符串需要开发者手动管理内存：<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>malloc</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>、<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strcpy</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>、<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strcat</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>、<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>free</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>……每一步都充满陷阱，比如忘记<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>free</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>导致的内存泄漏，或者<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strcpy</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>时目标缓冲区不够大导致的缓冲区溢出（这是多少安全漏洞的根源啊！）。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>完全自动化了这些。你只需要声明一个<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象，它就会在内部根据需要自动分配、扩容和释放内存。这让我可以把精力放在业务逻辑上，而不是繁琐且易错的内存操作。</p> <p>其次是<strong>丰富的API和操作符重载</strong>。C风格字符串的操作依赖于<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”><cstring></pre><div class=”contentsignin”></div></div>（或<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”><string.h></pre><div class=”contentsignin”></div></div>）中的一系列函数，比如<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strlen</pre><div class=”contentsignin”></div></div>、<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strcpy</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>、<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strcat</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>、<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>strcmp</pre><div class=”contentsignin”></div></div>。这些函数用起来比较原始，而且很多操作（比如拼接）需要反复调用，代码显得冗长。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>则提供了直观的成员函数，比如<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>append()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>、<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>insert()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>、<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>erase()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>，以及更自然的操作符重载，例如<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>+</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>和<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>+=</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>用于拼接，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>==</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>用于比较。这使得代码更简洁、更易读，也更符合直觉。</p> <p>再者是<strong>安全性</strong>。前面提到的缓冲区溢出是C风格字符串的“家常便饭”，而<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>通过其内部管理机制，大大降低了这类风险。例如，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>at()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>方法会进行边界检查，确保你不会访问到字符串范围之外的内存。虽然<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>[]</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>操作符没有边界检查，但整体而言，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>的设计理念就是为了减少这类常见的编程错误。</p> <p>最后，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>是<strong>面向对象</strong>的，它是一个拥有行为和状态的完整对象，而不是一个裸指针。这意味着它可以作为函数参数和返回值，行为符合C++的RAII（资源获取即初始化）原则，生命周期管理清晰。而C风格字符串作为函数参数时，常常需要同时传递长度信息，或者依赖空终止符，使用起来不如<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>那样自包含和安全。虽然在性能敏感的底层代码中，C风格字符串偶尔还有用武之地，但在绝大多数应用场景下，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>无疑是更现代、更安全、更高效的选择。</p> <h3>在实际项目中，如何高效地进行字符串查找与替换？</h3> <p>在实际开发中，字符串的查找和替换是家常便饭。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>提供了<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>find()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>、<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>rfind()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>和<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>replace()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>这些核心方法来应对，但要做到“高效”，这里面还是有些门道的。</p> <p><strong>查找：</strong><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>find()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>和<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>rfind()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>是你的主要<a >工具</a>。它们可以查找字符、C风格字符串或另一个<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象。一个常见的误区是，很多人只知道用它们来判断是否存在，而忽略了它们返回的是<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>size_t</pre><div class=”contentsignin”></div></div>类型的索引。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>std::string logLine = "ERROR: User ‘admin’ failed to login from 192.168.1.100"; size_t errorPos = logLine.find("ERROR"); if (errorPos != std::string::npos) { // 找到了错误标记 size_t userStart = logLine.find("User ‘"); if (userStart != std::string::npos) { size_t userEnd = logLine.find("’", userStart + 6); // 从’U’之后开始找下一个单引号 if (userEnd != std::string::npos) { std::string username = logLine.substr(userStart + 6, userEnd – (userStart + 6)); // username 现在是 "admin" } } }</pre><div class=”contentsignin”></div></div><p>这里<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>find()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>的第二个参数非常关键，它指定了搜索的起始位置。如果你要在一个长字符串中查找多个相同子串，或者从特定位置之后开始找，这个参数能大大提高效率，避免重复搜索已经检查过的部分。比如，解析csv文件时，每次找到一个逗号后，就从逗号的下一个位置开始查找下一个逗号。</p> <p><strong>替换：</strong><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>replace()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>方法同样强大，它能让你在指定位置替换特定长度的子字符串。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>std::string data = "Hello World!"; // 将 "World" 替换为 "C++" data.replace(6, 5, "C++"); // data 变为 "Hello C++!" // 也可以用迭代器 // auto it_start = data.begin() + 6; // auto it_end = data.begin() + 11; // data.replace(it_start, it_end, "C++");</pre><div class=”contentsignin”></div></div><p>当需要替换所有匹配项时，通常需要结合<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>find()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>和循环来实现：</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>std::string text = "This is a test string. This test is important."; std::string oldSub = "test"; std::string newSub = "example"; size_t pos = 0; while ((pos = text.find(oldSub, pos)) != std::string::npos) { text.replace(pos, oldSub.length(), newSub); pos += newSub.length(); // 从新替换的子串末尾开始继续查找 } // text 变为 "This is a example string. This example is important."</pre><div class=”contentsignin”></div></div><p>这里有个小技巧：<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>pos += newSub.length();</pre><div class=”contentsignin”></div></div>确保了如果替换后的新子串包含了旧子串（比如把”aa”替换成”aaa”），不会陷入死循环或者重复替换。当然，对于更复杂的模式匹配和替换，比如正则表达式，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::Regex</pre><div class=”contentsignin”></div></div>库是更好的选择，但对于简单的固定字符串查找替换，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>的方法就足够了，而且通常更高效。</p> <h3>性能考量：在大量字符串操作时，有哪些优化策略？</h3> <p>处理大量字符串时，性能问题很容易浮现。<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>虽然方便，但如果不注意，频繁的内存分配和数据拷贝会成为瓶颈。以下是我在实践中总结的一些优化策略：</p> <ol> <li> <p><strong>预分配内存：使用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>reserve()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div></strong> 这是最常见也最有效的优化手段之一。当你预见到一个字符串会变得很长，或者会进行大量的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>append()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>、<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>+=</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>操作时，提前调用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>reserve()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>来预留足够的内存空间，可以避免字符串在增长过程中频繁地重新分配内存和拷贝旧数据到新内存。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>std::string largeString; largeString.reserve(1024 * 1024); // 预留1MB空间 for (int i = 0; i < 100000; ++i) { largeString += “some data”; // 这里的+=操作会高效很多 }</pre><div class=”contentsignin”></div></div><p>如果没有<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>reserve()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>，每次<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>largeString</pre><div class=”contentsignin”></div></div>的容量不够时，它都需要分配一块更大的内存，然后把现有数据拷贝过去，再释放旧内存，这开销非常大。</p> </li> <li> <p><strong>避免不必要的拷贝：传递<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>const std::string&amp;</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div></strong> 在函数参数中，如果函数只是读取字符串内容而不修改它，务必使用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>const std::string&amp;</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>（常量引用）作为参数类型。这可以避免创建字符串的副本，从而节省内存和拷贝时间。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>void processString(const std::string&amp; data) { // 只读取 data，不修改 } // 而不是：void processString(std::string data) { … }</pre><div class=”contentsignin”></div></div><p>对于返回值，如果需要返回一个新创建的字符串，C++11引入的移动语义（Move Semantics）和返回值优化（RVO/NRVO）通常能很好地处理，避免额外的拷贝。</p> </li> <li> <p><strong>使用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string_view</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div> (C++17及更高版本)</strong><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string_view</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>是一个轻量级的非拥有字符串视图。它不拥有底层字符数据，只存储一个指向字符数据和其长度的指针。这意味着创建<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>string_view</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>或将其作为参数传递时，不会发生任何内存分配或数据拷贝。当你的操作只是“查看”字符串的某个部分，而不需要修改它，或者不需要其生命周期与视图绑定时，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>string_view</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>是极佳的选择。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>void parseToken(std::string_view token) { // token 只是一个视图，没有拷贝原始数据 } std::string original = "Long string to parse"; parseToken(original.substr(5, 6)); // 传递 "string" 的视图</pre><div class=”contentsignin”></div></div><p>这对于解析器、日志处理等场景，性能提升非常明显。</p> </li> <li> <p><strong>批量构建字符串：避免循环内频繁拼接</strong> 如果需要在循环中构建一个大字符串，不要每次迭代都进行拼接操作。这可能导致多次重新分配和拷贝。更好的做法是先收集所有需要拼接的片段，然后一次性构建，或者利用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>reserve()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>。</p><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=’brush:cpp;toolbar:false;’>// 差的实践 std::string result_bad; for (int i = 0; i < 1000; ++i) { result_bad += std::to_string(i) + “,”; } // 更好的实践 std::string result_good; result_good.reserve(1000 * (std::to_string(999).length() + 1)); // 预估总长度 for (int i = 0; i < 1000; ++i) { result_good += std::to_string(i); result_good += “,”; }</pre><div class=”contentsignin”></div></div><p>对于更复杂的格式化构建，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::stringstream</pre><div class=”contentsignin”></div></div>也是一个不错的选择，它提供了类似C风格<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>printf</pre><div class=”contentsignin”></div></div>的流式操作，内部也做了优化，但通常比直接的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>+=</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>操作略慢，因为它涉及到流的抽象层。</p> </li> <li><p><strong>谨慎使用<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>c_str()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>：</strong> 如前所述，<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>c_str()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>返回的指针在原<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>对象被修改后可能失效。如果你需要一个C风格字符串的副本，比如要传递给一个生命周期比原<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>std::string</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>更长的C API，或者C API会修改传入的字符串，那么应该显式地拷贝一份：<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>char* c_copy = new char[s.length() + 1]; strcpy(c_copy, s.c_str());</pre><div class=”contentsignin”></div></div> 记得用完后<div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>delete[]</pre><div class=”contentsignin”></div></div>。避免不必要的<div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><div class=”code” style=”position:relative; padding:0px; margin:0px;”><pre class=”brush:php;toolbar:false”>c_str()</pre><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div><div class=”contentsignin”></div></div>调用也能减少一些开销。</p></li> </ol> <p>这些策略并非相互独立，通常需要结合使用。在性能敏感的场景，Profiling（性能分析）工具是你的好朋友，它能帮你找出真正的性能瓶颈，而不是凭空猜测。</p>

以上就是C++字符串如何处理