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So, I have some PHP code that looks a bit like this:
<body> The ID is <?php echo $_GET["id"] . "!"; ?> </body> Now, when I pass an ID like http://localhost/myphp.php?id=26 it works alright, but if there is no ID like just http://localhost/myphp.php then it outputs:
The ID is Notice: Undefined index: id in C:\xampp\htdocs\myphp.php on line 9 ! I have searched for a way to fix this but I cannot find any way to check if a URL variable exists. I know there must be a way though.
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<? php //Method 1 if(! empty($_GET)) echo "exist"; else echo "do not exist"; //Method 2 echo "<br>"; if($_GET) echo "exist"; else echo "do not exist"; //Method 3 if(count($_GET)) echo "exist"; else echo "do not exist"; ?>
The isset() function checks whether a variable is set, which means that it has to be declared and is not NULL. This function returns true if the variable exists and is not NULL, otherwise it returns false.
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); 
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