unset

实例

销毁变量：

<span class="token php language-php"><span class="token delimiter important"><?php</span>  
<span class="token variable">$a</span> <span class="token operator">=</span> <span class="token string double-quoted-string">"Hello world!"</span><span class="token punctuation">;</span>  
<span class="token keyword">echo</span> <span class="token string double-quoted-string">"删除前变量 'a' 的值："</span> <span class="token operator">.</span> <span class="token variable">$a</span> <span class="token operator">.</span> <span class="token string double-quoted-string">"<br>"</span><span class="token punctuation">;</span>  
<span class="token keyword">unset</span><span class="token punctuation">(</span><span class="token variable">$a</span><span class="token punctuation">)</span><span class="token punctuation">;</span>  
<span class="token keyword">echo</span> <span class="token string double-quoted-string">"删除后变量 'a' 的值："</span> <span class="token operator">.</span> <span class="token variable">$a</span><span class="token punctuation">;</span>  
<span class="token delimiter important">?></span></span>

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