array_key_exists

名称:array_key_exists

分类:数组

所属语言:php

一句话介绍:检查指定的键名是否存在于数组中。

实例

例子 1

检查键名 "Volvo" 是否存在于数组中：

<span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token variable">$a</span><span class="token operator">=</span><span class="token keyword">array</span><span class="token punctuation">(</span><span class="token string double-quoted-string">"Volvo"</span><span class="token operator">=></span><span class="token string double-quoted-string">"XC90"</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"BMW"</span><span class="token operator">=></span><span class="token string double-quoted-string">"X5"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token function"></span><mark><span class="token function">array_key_exists</span><span class="token punctuation">(</span><span class="token string double-quoted-string">"Volvo"</span><span class="token punctuation">,</span><span class="token variable">$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 keyword">echo</span> <span class="token string double-quoted-string">"键存在！"</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token keyword">else</span>
  <span class="token punctuation">{</span>
  <span class="token keyword">echo</span> <span class="token string double-quoted-string">"键不存在！"</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

检查键名 "Toyota" 是否存在于数组中：

<span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token variable">$a</span><span class="token operator">=</span><span class="token keyword">array</span><span class="token punctuation">(</span><span class="token string double-quoted-string">"Volvo"</span><span class="token operator">=></span><span class="token string double-quoted-string">"XC90"</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"BMW"</span><span class="token operator">=></span><span class="token string double-quoted-string">"X5"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token function"></span><mark><span class="token function">key_exists</span><span class="token punctuation">(</span><span class="token string double-quoted-string">"Toyota"</span><span class="token punctuation">,</span><span class="token variable">$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 keyword">echo</span> <span class="token string double-quoted-string">"键存在！"</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token keyword">else</span>
  <span class="token punctuation">{</span>
  <span class="token keyword">echo</span> <span class="token string double-quoted-string">"键不存在！"</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token delimiter important">?></span></span>

亲自试一试

例子 3

检查整数键名 "0" 是否存在于数组中：

<span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token variable">$a</span><span class="token operator">=</span><span class="token keyword">array</span><span class="token punctuation">(</span><span class="token string double-quoted-string">"Volvo"</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"BMW"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token function"></span><mark><span class="token function">array_key_exists</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span><span class="token variable">$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 keyword">echo</span> <span class="token string double-quoted-string">"键存在！"</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token keyword">else</span>
  <span class="token punctuation">{</span>
  <span class="token keyword">echo</span> <span class="token string double-quoted-string">"键不存在！"</span><span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token delimiter important">?></span></span>

亲自试一试