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<?php // 获取user参数的值(如果为空，则用'nobody') $username = $_GET['user'] ?: 'nobody'; // 等价于: $username = isset($_GET['user']) ? $_GET['user'] : 'nobody'; echo $username;
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
Warning: Undefined array key "user" in /in/q8gPN on line 4 nobody
Output for 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.16 - 7.3.31, 7.4.0 - 7.4.33
Notice: Undefined index: user in /in/q8gPN on line 4 nobody
Output for 7.3.32 - 7.3.33
nobody
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176.27 ms | 401 KiB | 183 Q