How to verify if $_GET exists?
So, I have some PHP code that looks a bit like this:
<body>
The ID is
<?php
echo $_GET["id"] . "!";
?>
</body>
Now, when I pass an ID like http://localhost/myphp.php?id=26 it works alright, but if there is no ID like just http://localhost/myphp.php then it outputs:
The ID is
Notice: Undefined index: id in C:\xampp\htdocs\myphp.php on line 9
!
I have searched for a way to fix this but I cannot find any way to check if a URL variable exists. I know there must be a way though.
Answer
You can use isset function:
if(isset($_GET['id'])) {
// id index exists
}
You can create a handy function to return default value if index doesn't exist:
function Get($index, $defaultValue) {
return isset($_GET[$index]) ? $_GET[$index] : $defaultValue;
}
// prints "invalid id" if $_GET['id'] is not set
echo Get('id', 'invalid id');
You can also try to validate it at the same time:
function GetInt($index, $defaultValue) {
return isset($_GET[$index]) && ctype_digit($_GET[$index])
? (int)$_GET[$index]
: $defaultValue;
}
// prints 0 if $_GET['id'] is not set or is not numeric
echo GetInt('id', 0);