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php 判断恒量、变量、函数是否存在
- WBOYOriginal
- 2016-06-13 11:03:09690browse
php 判断常量、变量、函数是否存在
<?php/* 判断常量是否存在*/if (defined('CONSTANT1')) {echo CONSTANT1;}//判断变量是否存在if (isset($myvar)) {echo "$myvar.";}//判断函数是否存在if (function_exists('open')) {echo "存在函数open\n";} else {echo "函数open不存在\n";}?>
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