PHP 中首字母大小寫處理難題，lcfirst 函數可以怎麼解決？

<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-comment">// 前置與文章內容無關的代碼示例</span></span><span>
</span><span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span><span class="hljs-title">placeholderFunction</span></span><span>(</span><span><span class="hljs-params"></span></span><span>) {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"這是前置示例代碼，與文章內容無關。"</span></span><span>;
}
</span><span><span class="hljs-title function_ invoke__">placeholderFunction</span></span><span>();
</span><span><span class="hljs-meta">?></span></span><span>

<hr>

</span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-comment">// 文章正文開始</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"<h1>PHP 中首字母大小寫處理難題，lcfirst 函數可以怎麼解決？</h1>"</span></span><span>;

</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"<p>在 PHP 編程中，經常會遇到需要對字符串首字母進行大小寫處理的情況。例如，一個字符串的首字母需要小寫以符合某些命名規範，或者在處理用戶輸入時需要統一格式。</p>"</span></span><span>;

</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"<h2>問題描述</h2>"</span></span><span>;
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"<p>很多初學者會發現，雖然有 <code>strtoupper

\$str = 'HelloWorld';
\$newStr = lcfirst(\$str);
echo \$newStr; // 輸出'helloWorld'

\$str = '中文測試';
\$firstChar = mb_substr(\$str, 0, 1, 'UTF-8');
\$rest = mb_substr(\$str, 1, null, 'UTF-8');
\$newStr = mb_strtolower(\$firstChar, 'UTF-8') . \$rest;
echo \$newStr; // 輸出'中文測試'（首字母小寫處理）