[TOC] ## 实例 ``` // 只有通过 url 才能查询 // http://localhost/nanhe/test.php?email=1 //Email Found // http://localhost/nanhe/test.php?email //Email Found // http://localhost/nanhe/test.php //Email Not Found var_dump(filter_has_var(INPUT_GET, 'test')); //true; // 添加则无效 $_GET['test'] = 1; var_dump(filter_has_var(INPUT_GET, 'test')); //false; ```