usort

实例

使用用户自定义的比较函数对数组 $a 中的元素进行排序：

<span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token keyword">function</span> <span class="token function-definition function">my_sort</span><span class="token punctuation">(</span><span class="token variable">$a</span><span class="token punctuation">,</span><span class="token variable">$b</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 variable">$a</span><span class="token operator">==</span><span class="token variable">$b</span><span class="token punctuation">)</span> <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token variable">$a</span><span class="token operator"><</span><span class="token variable">$b</span><span class="token punctuation">)</span><span class="token operator">?</span><span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">:</span><span class="token number">1</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>

<span class="token variable">$a</span><span class="token operator">=</span><span class="token keyword">array</span><span class="token punctuation">(</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">8</span><span class="token punctuation">,</span><span class="token number">6</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token function"></span><mark><span class="token function">usort</span><span class="token punctuation">(</span><span class="token variable">$a</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"my_sort"</span><span class="token punctuation">)</span></mark><span class="token punctuation"></span><span class="token punctuation">;</span>
<span class="token delimiter important">?></span></span>

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