什麼是array_intersect_key？詳細介紹這個PHP 函數的作用和用法

gitbox 2025-09-02
<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// 前置無關部分</span></span><span>
</span><span><span class="hljs-variable">$dummyArray</span></span><span> = [</span><span><span class="hljs-string">"a"</span></span><span> =&gt; </span><span><span class="hljs-number">1</span></span><span>, </span><span><span class="hljs-string">"b"</span></span><span> =&gt; </span><span><span class="hljs-number">2</span></span><span>, </span><span><span class="hljs-string">"c"</span></span><span> =&gt; </span><span><span class="hljs-number">3</span></span><span>];
</span><span><span class="hljs-keyword">foreach</span></span><span> (</span><span><span class="hljs-variable">$dummyArray</span></span><span> </span><span><span class="hljs-keyword">as</span></span><span> </span><span><span class="hljs-variable">$key</span></span><span> =&gt; </span><span><span class="hljs-variable">$value</span></span><span>) {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-variable">$key</span></span><span> . </span><span><span class="hljs-string">" =&gt; "</span></span><span> . </span><span><span class="hljs-variable">$value</span></span><span> . </span><span><span class="hljs-string">"\n"</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">/**
 * 什麼是 array_intersect_key？詳細介紹這個 PHP 函數的作用和用法
 *
 * 在 PHP 中，array_intersect_key 是一個用於數組操作的重要函數。它的主要作用是
 * 返回一個數組，該數組包含了存在於多個數組中的相同鍵名的元素，而不關心它們的值。
 *
 * 基本語法：
 * array array_intersect_key(array $array1, array ...$arrays)
 *
 * 參數說明：
 * - $array1: 必須的，第一個輸入數組。
 * - ...$arrays: 可選的，其他一個或多個數組，用於比較鍵名。
 *
 * 返回值：
 * 返回一個數組，這個數組只包含 $array1 中那些鍵也出現在其他數組中的元素。
 *
 * 使用示例：
 */</span>

</span><span><span class="hljs-variable">$array1</span></span><span> = [
    </span><span><span class="hljs-string">"a"</span></span><span> =&gt; </span><span><span class="hljs-number">100</span></span><span>,
    </span><span><span class="hljs-string">"b"</span></span><span> =&gt; </span><span><span class="hljs-number">200</span></span><span>,
    </span><span><span class="hljs-string">"c"</span></span><span> =&gt; </span><span><span class="hljs-number">300</span></span><span>
];

</span><span><span class="hljs-variable">$array2</span></span><span> = [
    </span><span><span class="hljs-string">"b"</span></span><span> =&gt; </span><span><span class="hljs-number">400</span></span><span>,
    </span><span><span class="hljs-string">"c"</span></span><span> =&gt; </span><span><span class="hljs-number">500</span></span><span>,
    </span><span><span class="hljs-string">"d"</span></span><span> =&gt; </span><span><span class="hljs-number">600</span></span><span>
];

</span><span><span class="hljs-comment">// 取出兩個數組中相同鍵的元素</span></span><span>
</span><span><span class="hljs-variable">$result</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_intersect_key</span></span><span>(</span><span><span class="hljs-variable">$array1</span></span><span>, </span><span><span class="hljs-variable">$array2</span></span><span>);

</span><span><span class="hljs-title function_ invoke__">print_r</span></span><span>(</span><span><span class="hljs-variable">$result</span></span><span>);

<span class="hljs-comment">/**
 * 輸出結果：
 * Array
 * (
 *     [b] =&gt; 200
 *     [c] =&gt; 300
 * )
 *
 * 可以看到，只有鍵 "b" 和 "c" 存在於 $array1 和 $array2 中，因此最終返回的數組
 * 包含這些鍵對應的 $array1 中的值。
 *
 * 注意事項：
 * 1. array_intersect_key 只比較數組的鍵名，不比較鍵值。
 * 2. 函數可以同時接受多個數組進行比較，最終返回只保留那些在所有數組中都存在的鍵。
 *
 * 示例：多個數組
 */</span>
</span><span><span class="hljs-variable">$array3</span></span><span> = [
    </span><span><span class="hljs-string">"c"</span></span><span> =&gt; </span><span><span class="hljs-number">700</span></span><span>,
    </span><span><span class="hljs-string">"b"</span></span><span> =&gt; </span><span><span class="hljs-number">800</span></span><span>
];

</span><span><span class="hljs-variable">$result2</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_intersect_key</span></span><span>(</span><span><span class="hljs-variable">$array1</span></span><span>, </span><span><span class="hljs-variable">$array2</span></span><span>, </span><span><span class="hljs-variable">$array3</span></span><span>);

</span><span><span class="hljs-title function_ invoke__">print_r</span></span><span>(</span><span><span class="hljs-variable">$result2</span></span><span>);

<span class="hljs-comment">/**
 * 輸出結果：
 * Array
 * (
 *     [b] =&gt; 200
 *     [c] =&gt; 300
 * )
 *
 * 這裡，最终结果是保留同时存在於 $array1, $array2 和 $array3 中的鍵。
 *
 * 總結：
 * array_intersect_key 是處理數組鍵名交集的利器，尤其適用於在多維數組或關聯數組
 * 中篩選出指定的鍵，避免手動循環判斷，提高代碼效率和可讀性。
 */</span>
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>
array_intersect_key