使用rtrim 函數刪除字符串末尾特定字符的技巧

gitbox 2025-09-29
<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// 這裡是與文章內容無關的 PHP 代碼示例</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"歡迎閱讀 PHP 技巧分享！"</span></span><span>;
</span><span><span class="hljs-meta">?&gt;</span></span><span>

&lt;hr&gt;

</span><span><span class="hljs-meta">&lt;?php</span></span><span>
<span class="hljs-comment">/*
文章標題: 使用 rtrim 函數刪除字符串末尾特定字符的技巧
*/</span>

</span><span><span class="hljs-comment">// 在 PHP 中處理字符串時，經常會遇到需要刪除字符串末尾多餘字符的情況。</span></span><span>
</span><span><span class="hljs-comment">// rtrim 函數是 PHP 提供的一個非常實用的工具，可以針對字符串末尾進行精確的裁剪操作。</span></span><span>

</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"&lt;h1&gt;使用 rtrim 函數刪除字符串末尾特定字符的技巧&lt;/h1&gt;"</span></span><span>;

</span><span><span class="hljs-comment">// rtrim 基本用法</span></span><span>
<span class="hljs-comment">/*
文法:
string rtrim(string $str [, string $character_mask])
參數說明:
- $str: 要處理的字符串
- $character_mask: 指定要刪除的字符集合，默認刪除空白字符（空格、製表符、換行等）
返回值:
- 返回刪除指定字符後的字符串
*/</span>

</span><span><span class="hljs-comment">// 示例 1: 刪除末尾空白字符</span></span><span>
</span><span><span class="hljs-variable">$text1</span></span><span> = </span><span><span class="hljs-string">"Hello World!    "</span></span><span>;
</span><span><span class="hljs-variable">$clean1</span></span><span> = </span><span><span class="hljs-title function_ invoke__">rtrim</span></span><span>(</span><span><span class="hljs-variable">$text1</span></span><span>);
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"&lt;p&gt;原字符串: '<span class="hljs-subst">{$text1}</span></span></span><span>'&lt;/p&gt;";
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"&lt;p&gt;處理後: '<span class="hljs-subst">{$clean1}</span></span></span><span>'&lt;/p&gt;";

</span><span><span class="hljs-comment">// 示例 2: 刪除指定字符</span></span><span>
</span><span><span class="hljs-variable">$text2</span></span><span> = </span><span><span class="hljs-string">"filename.txtxxx"</span></span><span>;
</span><span><span class="hljs-variable">$clean2</span></span><span> = </span><span><span class="hljs-title function_ invoke__">rtrim</span></span><span>(</span><span><span class="hljs-variable">$text2</span></span><span>, </span><span><span class="hljs-string">"x"</span></span><span>); </span><span><span class="hljs-comment">// 刪除末尾所有 x</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"&lt;p&gt;原字符串: '<span class="hljs-subst">{$text2}</span></span></span><span>'&lt;/p&gt;";
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"&lt;p&gt;處理後: '<span class="hljs-subst">{$clean2}</span></span></span><span>'&lt;/p&gt;";

</span><span><span class="hljs-comment">// 示例 3: 刪除多個指定字符</span></span><span>
</span><span><span class="hljs-variable">$text3</span></span><span> = </span><span><span class="hljs-string">"abc123xyz123"</span></span><span>;
</span><span><span class="hljs-variable">$clean3</span></span><span> = </span><span><span class="hljs-title function_ invoke__">rtrim</span></span><span>(</span><span><span class="hljs-variable">$text3</span></span><span>, </span><span><span class="hljs-string">"123xyz"</span></span><span>); </span><span><span class="hljs-comment">// 刪除末尾的 1、2、3、x、y、z</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"&lt;p&gt;原字符串: '<span class="hljs-subst">{$text3}</span></span></span><span>'&lt;/p&gt;";
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"&lt;p&gt;處理後: '<span class="hljs-subst">{$clean3}</span></span></span><span>'&lt;/p&gt;";

</span><span><span class="hljs-comment">// 小技巧:</span></span><span>
</span><span><span class="hljs-comment">// 1. rtrim 只作用於字符串末尾，如果需要刪除開頭的字符，可以使用 ltrim。</span></span><span>
</span><span><span class="hljs-comment">// 2. 如果想同時刪除兩端字符，可以使用 trim。</span></span><span>
</span><span><span class="hljs-comment">// 3. character_mask 可以組合多個字符，rtrim 會刪除末尾連續出現的這些字符。</span></span><span>

</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"&lt;p&gt;通過以上示例，可以看出 rtrim 在處理字符串尾部特定字符時非常靈活，尤其適合清理用戶輸入或文件名後綴。&lt;/p&gt;"</span></span><span>;

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rtrim