array_keys

实例

例子 1

返回包含数组中所有键名的一个新数组：

<span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token variable">$a</span><span class="token operator">=</span><span class="token keyword">array</span><span class="token punctuation">(</span><span class="token string double-quoted-string">"Volvo"</span><span class="token operator">=></span><span class="token string double-quoted-string">"XC90"</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"BMW"</span><span class="token operator">=></span><span class="token string double-quoted-string">"X5"</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"Toyota"</span><span class="token operator">=></span><span class="token string double-quoted-string">"Highlander"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token function">print_r</span><span class="token punctuation">(</span><span class="token function"></span><mark><span class="token function">array_keys</span><span class="token punctuation">(</span><span class="token variable">$a</span><span class="token punctuation">)</span></mark><span class="token punctuation"></span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token delimiter important">?></span></span>

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例子 2

使用 value 参数：

<span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token variable">$a</span><span class="token operator">=</span><span class="token keyword">array</span><span class="token punctuation">(</span><span class="token string double-quoted-string">"Volvo"</span><span class="token operator">=></span><span class="token string double-quoted-string">"XC90"</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"BMW"</span><span class="token operator">=></span><span class="token string double-quoted-string">"X5"</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"Toyota"</span><span class="token operator">=></span><span class="token string double-quoted-string">"Highlander"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token function">print_r</span><span class="token punctuation">(</span><span class="token function"></span><mark><span class="token function">array_keys</span><span class="token punctuation">(</span><span class="token variable">$a</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"Highlander"</span><span class="token punctuation">)</span></mark><span class="token punctuation"></span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token delimiter important">?></span></span>

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例子 3

使用 strict 参数（false）：

<span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token variable">$a</span><span class="token operator">=</span><span class="token keyword">array</span><span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">,</span><span class="token number">20</span><span class="token punctuation">,</span><span class="token number">30</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"10"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token function">print_r</span><span class="token punctuation">(</span><span class="token function"></span><mark><span class="token function">array_keys</span><span class="token punctuation">(</span><span class="token variable">$a</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"10"</span><span class="token punctuation">,</span><span class="token constant boolean">false</span><span class="token punctuation">)</span></mark><span class="token punctuation"></span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token delimiter important">?></span></span>

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例子 4

使用 strict 参数（true）：

<span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token variable">$a</span><span class="token operator">=</span><span class="token keyword">array</span><span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">,</span><span class="token number">20</span><span class="token punctuation">,</span><span class="token number">30</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"10"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token function">print_r</span><span class="token punctuation">(</span><span class="token function"></span><mark><span class="token function">array_keys</span><span class="token punctuation">(</span><span class="token variable">$a</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"10"</span><span class="token punctuation">,</span><span class="token constant boolean">true</span><span class="token punctuation">)</span></mark><span class="token punctuation"></span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token delimiter important">?></span></span>

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