# instanceof 判断后代子类 instanceof 判断后代子类 > 判断左边的对象是否是右边类的后代(实例化的结果) - - - - - - ``` <pre class="calibre17">``` class <span class="token4">Person</span> <span class="token3">{</span> public $name <span class="token1">=</span> <span class="token2">'苍老师'</span><span class="token3">;</span> <span class="token3">}</span> class <span class="token4">Boy</span> extends <span class="token4">Person</span> <span class="token3">{</span> public $name <span class="token1">=</span> <span class="token2">'小泽泽'</span><span class="token3">;</span> <span class="token3">}</span> class <span class="token4">Girl</span> <span class="token3">{</span> public $name <span class="token1">=</span> <span class="token2">'小静静'</span><span class="token3">;</span> <span class="token3">}</span> <span class="token">// 实例化Person类 </span> $p <span class="token1">=</span> <span class="token5">new</span> <span class="token4">Person</span><span class="token3">;</span> $b <span class="token1">=</span> <span class="token5">new</span> <span class="token4">Boy</span><span class="token3">;</span> $g <span class="token1">=</span> <span class="token5">new</span> <span class="token4">Girl</span><span class="token3">;</span> var\<span class="token4">_dump</span><span class="token3">(</span>$p <span class="token5">instanceof</span> <span class="token4">Person</span><span class="token3">)</span><span class="token3">;</span> <span class="token">// true </span> var\<span class="token4">_dump</span><span class="token3">(</span>$b <span class="token5">instanceof</span> <span class="token4">Person</span><span class="token3">)</span><span class="token3">;</span> <span class="token">// true</span> var\<span class="token4">_dump</span><span class="token3">(</span>$g <span class="token5">instanceof</span> <span class="token4">Person</span><span class="token3">)</span><span class="token3">;</span> <span class="token">// false</span> var\<span class="token4">_dump</span><span class="token3">(</span>$p <span class="token5">instanceof</span> <span class="token4">Boy</span><span class="token3">)</span><span class="token3">;</span> <span class="token">// false</span> ``` ```