# Countable的使用 ### Countable的用法 #### 首先在extend目录创建A.php 并引入Countable类 ``` <pre class="calibre13">``` <span class="token"><</span><span class="token">?</span>php <span class="token2">class</span> <span class="token3">A</span> <span class="token2">implements</span> <span class="token3">Countable</span> <span class="token1">{</span> <span class="token2">public</span> <span class="token2">function</span> <span class="token3">count</span><span class="token1">(</span><span class="token1">)</span><span class="token1">{</span> <span class="token2">return</span> <span class="token4">'111'</span><span class="token1">;</span> <span class="token1">}</span> <span class="token1">}</span> ``` ``` #### 然后在控制中调用 ``` <pre class="calibre14">``` <span class="token"><</span><span class="token">?</span>php namespace app\index\controller<span class="token1">;</span> <span class="token2">class</span> <span class="token3">Index</span> <span class="token1">{</span> <span class="token2">public</span> <span class="token2">function</span> <span class="token3">index</span><span class="token1">(</span><span class="token1">)</span> <span class="token1">{</span> $obj <span class="token">=</span> <span class="token2">new</span> <span class="token3"><span class="token1">\</span>A</span><span class="token1">(</span><span class="token1">)</span><span class="token1">;</span> <span class="token6">// echo $obj->count();</span> echo <span class="token3">count</span><span class="token1">(</span>$obj<span class="token1">)</span><span class="token1">;</span> <span class="token6">//使用Countable调用方法</span> <span class="token1">}</span> <span class="token1">}</span> ``` ```