how can I dected if URL has variable?

Posted on 2016-11-09
Medium Priority
Last Modified: 2016-11-09
Hello guys,

I have this code in my php file:

	$parc = $_GET['cod']; 	

Open in new window

the cod is a variable that comes from my URL, like: www.teachmenow.com.br?cod=002

but, sometimes the link doesn't have the variable, then I am getting an error:

Undefined index: cod

is there any way to prevent if URL came with variable or not?

Question by:hidrau
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 2
  • 2
LVL 35

Expert Comment

ID: 41880633
When it is a mandatory parameter, then use a redirect. Depending on your stack, this should be placed at the web server level, if possible.
LVL 111

Accepted Solution

Ray Paseur earned 2000 total points
ID: 41880637
$cod = !empty($_GET['cod']) ? $_GET['cod'] : FALSE;
if ($cod) { /* YOU HAVE A VARIABLE IN THE URL */}

Open in new window

If you're new to PHP and want to learn the language, this article can help you get started.  Just skip over the parts you already know from other programming languages or computer science courses.

Author Comment

ID: 41880722
Hello Ray,

I had found something like this:

if isset($_GET['cod']) {
		$parc = 'VD001'
	} else {
		$parc = $_GET['cod']

Open in new window

What do you think about?

Thanks for the link
Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

LVL 111

Assisted Solution

by:Ray Paseur
Ray Paseur earned 2000 total points
ID: 41880750
That looks a little bit backwards to me.  As I understand the intended logic, the external variable should be the controlling factor, otherwise a default value will be used.

The Ternary operator is useful for things like this.  This page is long, but it's required reading for anyone who writes PHP code.

Here is how I might write the expressions
$parc = !empty($_GET['cod']) ? $_GET['cod'] : 'VD001';

Open in new window

Here is the narrative:
1. Inspect $__GET['cod'] with the empty() function.  If that returns FALSE, there is information in $_GET['cod']
2. When empty() returns FALSE, !empty() [said "not-empty"] returns TRUE
3. With !empty() === TRUE, assign the value in $_GET['cod'] to $parc
4. With !empty() === FALSE, assign the literal string 'VD001' to $parc
LVL 35

Expert Comment

ID: 41880774
First of all: do you have a working backup? Do you have a test system?

Cause you currently allow SQL injection...


Author Closing Comment

ID: 41880808
Thanks a lot
LVL 111

Expert Comment

by:Ray Paseur
ID: 41880814
Thanks for the points.  I think ste5an may have a good point about the risks of SQL injection.  This article shows some ways of preventing it.

Featured Post

Secure Your WordPress Site: 5 Essential Approaches

WordPress is the web's most popular CMS, but its dominance also makes it a target for attackers. Our eBook will show you how to:

Prevent costly exploits of core and plugin vulnerabilities
Repel automated attacks
Lock down your dashboard, secure your code, and protect your users

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

These days socially coordinated efforts have turned into a critical requirement for enterprises.
Password hashing is better than message digests or encryption, and you should be using it instead of message digests or encryption.  Find out why and how in this article, which supplements the original article on PHP Client Registration, Login, Logo…
Learn how to match and substitute tagged data using PHP regular expressions. Demonstrated on Windows 7, but also applies to other operating systems. Demonstrated technique applies to PHP (all versions) and Firefox, but very similar techniques will w…
This tutorial will teach you the core code needed to finalize the addition of a watermark to your image. The viewer will use a small PHP class to learn and create a watermark.
Suggested Courses

770 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question