Trouble with "if then"

[ryland22]

I have a dynamic page where I'm trying to check if 2 variable have been passed to it ("rowbegin" and "rowend"), if those variables have not been passed to the page, then I want to assign "rowbegin" a value of "0" and "rowend" a value of "50".

I keep getting the following error:

Undefined index: rowbegin in threads5.php on line X

Below is my code:

<?php
$_GET["rowbegin"];
$_GET["rowend"];

if (is_null("rowbegin")) {
  $rowbegin = 0;
  $rowend = 50;
}
?>

[Merve]

Your code should read:

<?php
if (is_null($_GET['rowbegin'])) {
$_GET['rowbegin'] = 0;
$_GET['rowend'] = 50;
}
?>

[ryland22]

Merve, that didn't work, I still get:

Undefined index: rowbegin in threads5.php on line 7

I think the problem is that the variable "rowbegin" is not being passed to the page at all. How do I perform a check to see if a variable is being passed- if it's not being passed, then I want to create the variable and assign a value to it?

[Merve]

In that case:

<?php
if (isset($_GET['rowbegin'])) {
     $_GET['rowbegin'] = 0;
     $_GET['rowend'] = 50;
}
?> 

[ryland22]

Hmmm, now when I try to use the variable later in the code, I am getting another error:

Undefined variable: rowbegin in threads5.php on line 51

<?php 
if (isset($_GET['rowbegin'])) { 
     $_GET['rowbegin'] = 0; 
     $_GET['rowend'] = 50; 
} 
?> 

blah blah

<?php
echo $rowbegin;
?>

[ryland22]

This seems to have done the trick:

<?php 
if (!isset($_GET['rowbegin'])) { 
     $rowbegin = 0; 
     $rowend = 50; 
} 
else{
$rowbegin = $_GET['rowbegin'];
$rowend = $_GET['rowend'];

}
?> 

Thank you for your assistance Merve.