How to verify if $_GET exists?

Question

So, I have some PHP code that looks a bit like this:

    The ID is 

    


         


        

Answer 1

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);