array_key_exists

名稱:array_key_exists

分類:數組

所屬語言:php

一句話介紹:檢查指定的鍵名是否存在於數組中。

實例

例子1

檢查鍵名"Volvo" 是否存在於數組中：

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

親自試一試

例子2

檢查鍵名"Toyota" 是否存在於數組中：

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

親自試一試

例子3

檢查整數鍵名"0" 是否存在於數組中：

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

親自試一試