PHP check if url parameter exists

问题:

I have a URL which i pass parameters into

example/success.php?id=link1

I use php to grab it

$slide = ($_GET["id"]);

then an if statement to display content based on parameter

<?php  if($slide == 'link1') { ?>
   //content
 } ?>

Just need to know in PHP how to say, if the url param exists grab it and do the if function, if it doesn't exist do nothing.

Thanks Guys

回答1:

Use isset()

$matchFound = ( isset($_GET["id"]) && trim($_GET["id"]) == 'link1' );
$slide = $matchFound ? trim ($_GET["id"]) : '';

EDIT: This is added for the completeness sake. $_GET in php is a reserved variable that is an associative array. Hence, you could also make use of 'array_key_exists(mixed $key, array $array)'. It will return a boolean that the key is found or not. So, the following also will be okay.

$matchFound = ( array_key_exists("id", $_GET)) && trim($_GET["id"]) == 'link1' );
$slide = $matchFound ? trim ($_GET["id"]) : '';

回答2:

if(isset($_GET['id']))
{
    // Do something
}

You want something like that

回答3:

It is not quite clear what function you are talking about and if you need 2 separate branches or one. Assuming one:

Change your first line to

$slide = '';
if (isset($_GET["id"]))
{
    $slide = $_GET["id"];
}

回答4:

Here is the PHP code to check if 'id' parameter exists in the URL or not:

if(isset($_GET['id']))
{
   $slide = $_GET['id'] // Getting parameter value inside PHP variable
}

I hope it will help you.

回答5:

Why not just simplify it to if($_GET['id']). It will return true or false depending on status of the parameter's existence.