如何定义包含$ _GET [duplicate]的变量

Question

This question already has an answer here:

• “Notice: Undefined variable”, “Notice: Undefined index”, and “Notice: Undefined offset” using PHP 28 answers

How do you define a variable which holds the $_GET['value']; ?

I get this error UNDEFINED INDEX: cat IN C... ON LINE 20 while doing this:

$cat = $_GET['cat'];
$cat_array = array('users', 'projects', 'roles', 'library', 'bugs');

How can I define the $cat

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Answer 1

Check variable has that index & value first then assign.

isset($_GET['cat']){
      $cat = $_GET['cat'];
}

Always check array index before use it.

You can read more about isset in the PHP documentation.

Let me know for more help.