I'm trying to check to see if a $\_GET value is available AND equal to 1 but the error is that the index is not defined.

```
<?php if ((isset($_GET['success'])) ||  ($_GET['success'] == 1)) { ?>
Do Something
<?php } ?>

```

Why is this a problem? I'm checking to see if it exists and then if it equals one and if so , do something.

Is there a better way to achieve this goal?