如何使用PHP array_keys()提取數組的所有鍵名？使用示例分析

<span><span><span class="hljs-meta"><?php</span></span><span> </span><span><span class="hljs-comment">// 这部分代码与文章内容无关，仅作为示例展示</span></span><span> </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"开始文章内容展示"</span></span><span>; </span><span><span class="hljs-meta">?></span></span><span> <hr> 如何使用PHP </span><span><span class="hljs-title function_ invoke__">array_keys</span></span><span>()提取数组的所有键名？使用示例分析 在PHP开发中，数组是一种非常重要的数据结构。经常需要对数组的键名进行操作，比如提取数组中所有的键名，方便后续处理。PHP内置了一个非常实用的函数——`</span><span><span class="hljs-title function_ invoke__">array_keys</span></span><span>()`，专门用来提取数组的键名。 </span><span><span class="hljs-comment">### 一、array_keys()函数简介</span></span><span> `</span><span><span class="hljs-title function_ invoke__">array_keys</span></span><span>()`函数的作用是返回输入数组中所有的键名组成的新数组。其基本语法如下： ```php </span><span><span class="hljs-keyword">array</span></span><span> </span><span><span class="hljs-title function_ invoke__">array_keys</span></span><span>(</span><span><span class="hljs-keyword">array</span></span><span> </span><span><span class="hljs-variable">$array</span></span><span>, </span><span><span class="hljs-keyword">mixed</span></span><span> </span><span><span class="hljs-variable">$search_value</span></span><span> = </span><span><span class="hljs-literal">null</span></span><span>, </span><span><span class="hljs-keyword">bool</span></span><span> </span><span><span class="hljs-variable">$strict</span></span><span> = </span><span><span class="hljs-literal">false</span></span><span>) </span></span>

• ：必填，輸入的數組。

• $search_value （可選）：如果指定了該值，函數只返回值等於該值的鍵名。

• $strict （可選）：是否嚴格比較（包括類型），默認false。

二、基本用法示例

<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-variable">$person</span></span><span> = [
    </span><span><span class="hljs-string">"name"</span></span><span> =&gt; </span><span><span class="hljs-string">"小明"</span></span><span>,
    </span><span><span class="hljs-string">"age"</span></span><span> =&gt; </span><span><span class="hljs-number">25</span></span><span>,
    </span><span><span class="hljs-string">"gender"</span></span><span> =&gt; </span><span><span class="hljs-string">"男"</span></span><span>
];

</span><span><span class="hljs-variable">$keys</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_keys</span></span><span>(</span><span><span class="hljs-variable">$person</span></span><span>);
</span><span><span class="hljs-title function_ invoke__">print_r</span></span><span>(</span><span><span class="hljs-variable">$keys</span></span><span>);
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>

輸出結果：

 <span><span>Array
(
    [</span><span><span class="hljs-meta">0</span></span><span>] =&gt; name
    [</span><span><span class="hljs-meta">1</span></span><span>] =&gt; age
    [</span><span><span class="hljs-meta">2</span></span><span>] =&gt; gender
)
</span></span>

可以看到， array_keys()返回了數組$person所有的鍵名，組成了一個索引數組。

三、指定值提取對應鍵名

array_keys()還支持第二個參數，傳入一個值後，只返回該值對應的鍵名。

 <span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-variable">$array</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">100</span></span><span>,
    </span><span><span class="hljs-string">"d"</span></span><span> =&gt; </span><span><span class="hljs-number">300</span></span><span>
];

</span><span><span class="hljs-variable">$keys</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_keys</span></span><span>(</span><span><span class="hljs-variable">$array</span></span><span>, </span><span><span class="hljs-number">100</span></span><span>);
</span><span><span class="hljs-title function_ invoke__">print_r</span></span><span>(</span><span><span class="hljs-variable">$keys</span></span><span>);
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>

輸出：

 <span><span>Array
(
    [</span><span><span class="hljs-meta">0</span></span><span>] =&gt; a
    [</span><span><span class="hljs-meta">1</span></span><span>] =&gt; c
)
</span></span>

這裡array_keys()返回了所有值為100的鍵名。

四、嚴格模式的使用

當需要區分類型時，可以開啟嚴格模式：

 <span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-variable">$array</span></span><span> = [
    </span><span><span class="hljs-string">"a"</span></span><span> =&gt; </span><span><span class="hljs-string">"100"</span></span><span>,
    </span><span><span class="hljs-string">"b"</span></span><span> =&gt; </span><span><span class="hljs-number">100</span></span><span>,
    </span><span><span class="hljs-string">"c"</span></span><span> =&gt; </span><span><span class="hljs-number">200</span></span><span>
];

</span><span><span class="hljs-variable">$keys</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_keys</span></span><span>(</span><span><span class="hljs-variable">$array</span></span><span>, </span><span><span class="hljs-number">100</span></span><span>, </span><span><span class="hljs-literal">true</span></span><span>);
</span><span><span class="hljs-title function_ invoke__">print_r</span></span><span>(</span><span><span class="hljs-variable">$keys</span></span><span>);
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>

輸出：

 <span><span>Array
(
    [</span><span><span class="hljs-meta">0</span></span><span>] =&gt; b
)
</span></span>

由於嚴格模式下不進行類型轉換，只有值類型和值都相同的鍵名才會被返回。

五、總結

• array_keys()用於提取數組中所有鍵名，返回一個包含鍵名的新數組。

• 可以通過第二個參數限制返回指定值對應的鍵名。

• 第三個參數開啟嚴格比較，區分類型。

• 該函數在數據篩選、重組數組結構時非常有用。

掌握array_keys() ，可以讓你在PHP數組操作中更靈活高效，提升代碼質量。

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• 相關標籤:

  array_keys