如何使用PHP array_keys()提取数组的所有键名？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，输入的数组。

• $search_value（可选）：如果指定了该值，函数只返回值等于该值的键名。

• $strict（可选）：是否严格比较（包括类型），默认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>

输出结果：

<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()返回了数组$person所有的键名，组成了一个索引数组。

三、指定值提取对应键名

array_keys()还支持第二个参数，传入一个值后，只返回该值对应的键名。

<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>

输出：

<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>

这里array_keys()返回了所有值为100的键名。

四、严格模式的使用

当需要区分类型时，可以开启严格模式：

<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>

输出：

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

由于严格模式下不进行类型转换，只有值类型和值都相同的键名才会被返回。

五、总结

• array_keys()用于提取数组中所有键名，返回一个包含键名的新数组。

• 可以通过第二个参数限制返回指定值对应的键名。

• 第三个参数开启严格比较，区分类型。

• 该函数在数据筛选、重组数组结构时非常有用。

掌握array_keys()，可以让你在PHP数组操作中更灵活高效，提升代码质量。

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• 相关标签:

  array_keys