Question about is_null

I was wondering if the is_null fuction can be used in the following code. If someone were to link out.php?sid=1 and no "id" was input for the following code, I would like the output for link2=.$link2[$id] to be the same as link1=.$link1[$sid]

Out.php

<?php
  $id = $_GET['id'];
  $sid = $_GET['sid'];
  $link1 = array(
    "1" => "http://www.example-affiliate.com",
    "2" => "http://www.test-affiliate.com",
    );
  $link2 = array(
    "1" => "http://www.example.com/deeplink.html",
    "2" => "http://www.test.com/deeplink.html",
);

  header("Location: out2.php?link1=.$link1[$sid]&link2=.$link2[$id]");
  exit;
?> 

PHP:

if I were to replace the last 2 lines of code with the following code would it work?

  
  if ($id==is_null) {
    header("Location: out2.php?link1=.$link1[$sid]&link2=.$link1[$sid]");
  }
  else {
    header("Location: out2.php?link1=.$link1[$sid]&link2=.$link2[$id]");
  }
  exit;

PHP:

 

I prefer empty myself.

if(!empty($_GET['id']))
{
   //do stuff
}

Code (markup):

 

which one is faster? And the code looks correct (besides me needing to remove the dots in the outbound link) ?

 

Read the user-contributed notes for each function and decide which is a better fit for how you think.

http://www.php.net/is_null
http://www.php.net/empty

 

is null is a function, it will return a boolean so comparing something to it's reference won't do what you're expecting

$var = null;
echo is_null($var) // true
$var = '';
echo is_null($var) // false

Code (markup):

In your case you might actually want to do two things:

1. array_key_exists() to make sure the parameter you're looking for was passed at all
2. If it was passed, use strlen() to make sure it has length.

 

Ok, i put the following code in and it works

<?php
  $id = $_GET['id'];
  $sid = $_GET['sid'];
  $link1 = array(
    "1" => "http://www.example-affiliate.com",
    "2" => "http://www.test-affiliate.com",
    );
  $link2 = array(
    "1" => "http://www.example.com/deeplink.html",
    "2" => "http://www.test.com/deeplink.html",
);

	if( empty($_GET['id'])) {
		header("Location: out2.php?link1=$link1[$sid]&link2=$link1[$sid]");
	}
  	else {
		header("Location: out2.php?link1=$link1[$sid]&link2=$link2[$id]");
	}
  exit;

?> 

PHP:

The more I learn about php the more I want to do. I figure that sometimes the out2.php page is not needed. From what i am gathering, ! is "not" so I tried the following code but it does nothing. When a link is input, it just outputs a blank page with the page source blank too. What have I done wrong?

<?php
  $id = $_GET['id'];
  $sid = $_GET['sid'];
  $link1 = array(
    "1" => "http://www.example-affiliate.com",
    "2" => "http://www.test-affiliate.com",
    );
  $link2 = array(
    "1" => "http://www.example.com/deeplink.html",
    "2" => "http://www.test.com/deeplink.html",
);
	
	if( empty($_GET['id']) && !empty($_GET['sid']) {
		header("Location: outt2.php?link1=$link1[$sid]&link2=$link1[$sid]");
	}  	elseif( !empty($_GET['id']) && !empty($_GET['sid']) {
		header("Location: outt2.php?link1=$link1[$sid]&link2=$link2[$id]");
	}	elseif( !empty($_GET['id']) && empty($_GET['sid']) {
		header("Location: ".$link2[$id]);
	}	else { 
		header("Location: index.php");
	}
  exit;


?> 

PHP:

 

<?php
	// Check if they exist, have values, and force them to be numbers
	$id = empty($_GET['id']) ? 0 : intval($_GET['id']);
	$sid = empty($_GET['sid']) ? 0 : intval($_GET['sid']);
	if(!$id && !$sid)
	{// No sense in going any further if neither exist
		header('Location: index.php');
		exit;
	}
	
	// List of valid indexes for $sid
	$link1 = array(
		1 => 'http://www.example-affiliate.com',
		2 => 'http://www.test-affiliate.com',
	);
	// List of valid indexes for $id
	$link2 = array(
		1 => 'http://www.example.com/deeplink.html',
		2 => 'http://www.test.com/deeplink.html',
	);
	
	// Check if there's valid entries in the lists
	$id = isset($link2[$id]) ? $link2[$id] : 0;
	$sid = isset($link1[$sid]) ? $link1[$sid] : 0;
	if(!$id && !$sid)
	{// No sense in going any further if unknown numbers were given
		header('Location: index.php');
		exit;
	}
	
	// Reuseable
	$header = 'Location: outt2.php?link1=%s&link2=%s';
	
	// Where to ?
	if(!$id && $sid)
	{
		$header = sprintf($header, $sid, $sid);
	}
	else if($id && !$sid)
	{
		$header = "Location: $id";
	}
	else
	{
		$header = sprintf($header, $sid, $id);
	}
	
	// Home James !
	header($header);
?>

PHP:

 

Thanks. Some of that brings me back a couple of years to the matlab coding that I had to do for my engineering classes.