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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>
: Requis, tableau d'entrée.
$ search_value (facultatif): Si cette valeur est spécifiée, la fonction renvoie uniquement le nom de la clé dont la valeur est égale à cette valeur.
$ strict (facultatif): s'il faut comparer strictement (y compris les types), faux par défaut.
<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-variable">$person</span></span><span> = [
</span><span><span class="hljs-string">"name"</span></span><span> => </span><span><span class="hljs-string">"Xiao Ming"</span></span><span>,
</span><span><span class="hljs-string">"age"</span></span><span> => </span><span><span class="hljs-number">25</span></span><span>,
</span><span><span class="hljs-string">"gender"</span></span><span> => </span><span><span class="hljs-string">"mâle"</span></span><span>
];
</span><span><span class="hljs-variable">$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">?></span></span><span>
</span></span>Résultat de sortie:
<span><span>Array
(
[</span><span><span class="hljs-meta">0</span></span><span>] => name
[</span><span><span class="hljs-meta">1</span></span><span>] => age
[</span><span><span class="hljs-meta">2</span></span><span>] => gender
)
</span></span>Comme vous pouvez le voir, array_keys () renvoie tous les noms clés de la personne $ et forme un tableau d'index.
array_keys () prend également en charge un deuxième paramètre. Après avoir transmis une valeur, seul le nom de clé correspondant à la valeur est renvoyé.
<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-variable">$array</span></span><span> = [
</span><span><span class="hljs-string">"a"</span></span><span> => </span><span><span class="hljs-number">100</span></span><span>,
</span><span><span class="hljs-string">"b"</span></span><span> => </span><span><span class="hljs-number">200</span></span><span>,
</span><span><span class="hljs-string">"c"</span></span><span> => </span><span><span class="hljs-number">100</span></span><span>,
</span><span><span class="hljs-string">"d"</span></span><span> => </span><span><span class="hljs-number">300</span></span><span>
];
</span><span><span class="hljs-variable">$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">?></span></span><span>
</span></span>Sortir:
<span><span>Array
(
[</span><span><span class="hljs-meta">0</span></span><span>] => a
[</span><span><span class="hljs-meta">1</span></span><span>] => c
)
</span></span>Ici, array_keys () renvoie tous les noms de clés avec une valeur de 100 .
Lorsque vous devez distinguer les types, vous pouvez activer le mode strict:
<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-variable">$array</span></span><span> = [
</span><span><span class="hljs-string">"a"</span></span><span> => </span><span><span class="hljs-string">"100"</span></span><span>,
</span><span><span class="hljs-string">"b"</span></span><span> => </span><span><span class="hljs-number">100</span></span><span>,
</span><span><span class="hljs-string">"c"</span></span><span> => </span><span><span class="hljs-number">200</span></span><span>
];
</span><span><span class="hljs-variable">$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">?></span></span><span>
</span></span>Sortir:
<span><span>Array
(
[</span><span><span class="hljs-meta">0</span></span><span>] => b
)
</span></span>Étant donné que la conversion de type n'est pas effectuée en mode strict, seuls les noms de clés avec le même type de valeur et la même valeur seront renvoyés.
array_keys () est utilisé pour extraire tous les noms de clés du tableau et renvoyer un nouveau tableau contenant les noms de clés.
Le nom de clé correspondant à la valeur spécifiée peut être renvoyé par la deuxième limite de paramètre.
Le troisième paramètre permet une comparaison stricte et distingue les types.
Cette fonction est très utile lors du filtrage des données et de la réorganisation des structures du tableau.
La maîtrise Array_Keys () peut vous rendre plus flexible et efficace dans les opérations PHP Array et améliorer la qualité du code.
<hr> <? php // L'article se termine, pas de contenu à l'avenir?> <span></span>
Étiquettes associées:
array_keys
