array_key_exists

Name:array_key_exists

Category:Array

Programming Language:php

One-line Description:Checks whether the specified key name exists in the array.

Example

Example 1

Check whether the key name "Volvo" exists in the array:

 <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">"The key exists!"</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">"The key does not exist!"</span> <span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token delimiter important">?></span>

Try it yourself

Example 2

Check whether the key name "Toyota" exists in the array:

 <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">"The key exists!"</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">"The key does not exist!"</span> <span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token delimiter important">?></span>

Try it yourself

Example 3

Check whether the integer key name "0" exists in the array:

 <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">"The key exists!"</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">"The key does not exist!"</span> <span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token delimiter important">?></span>

Try it yourself