Square of 5 is: 25
Hello, John!<br />
<b>Notice</b>:  Undefined index: username in <b>D:\phpStudy\WWW\work\20250919\oa_xk\php copy 2\php5.php</b> on line <b>85</b><br />
Array
(
    [id] => 3
    [name] => Bob
    [age] => 22
    [isAdult] => 1
)