empty

Example

Checks whether a variable is empty. Also check whether the variable has been set/declared:

 <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 number">0</span> <span class="token punctuation">;</span>  
  
<span class="token comment">// The result is true, because $a is empty</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span> <span class="token keyword">empty</span> <span class="token punctuation">(</span> <span class="token variable">$a</span> <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">"variable &#39;a&#39; is empty.<br>"</span> <span class="token punctuation">;</span>  
<span class="token punctuation">}</span>  
  
<span class="token comment">// The result is true because $a is set</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span> <span class="token keyword">isset</span> <span class="token punctuation">(</span> <span class="token variable">$a</span> <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">"variable &#39;a&#39; is set"</span> <span class="token punctuation">;</span>  
<span class="token punctuation">}</span>  
<span class="token delimiter important">?></span></span>

Try it yourself