PHP error page problem

Question

I can't figure out why this script isn't working.

<?php

if (($_GET['p'] != 'index') && 
    ($_GET['p'] != 'reg') && 
    ($_GET['p'] != 'login') && 
    ($_GET['p'] != 'ad') && 
    (!isset($_GET['p']))):
?>

<?php endif; ?>

I want to not display the error page if the $_GET is not set, which in my experience (!isset($_GET['p'])) should do.

You might want to rephrase your title to provide a more accurate description of the problem. A better description will attract more and better answers ! — Tristan Dubé
– Tristan Dubé, Commented Sep 25, 2011 at 18:42
If you're wanting to check an !isset($_GET['p']), put it first in the list BEFORE checking equality. — Jared Farrish
– Jared Farrish, Commented Sep 25, 2011 at 18:44
Also, I don't know why you have so many parentheticals grouping single conditions. They're superfluous to what is happening. — Jared Farrish
– Jared Farrish, Commented Sep 25, 2011 at 18:47
By "$_GET is not set" Do you mean you want !isset($_GET['p']) to evaluate to TRUE when the get request is like this ? or when it is ?p=? — Shef
– Shef, Commented Sep 25, 2011 at 19:01

Joseph Silber · Accepted Answer · 2011-09-25 19:14:36Z

5

If $_GET['p'] is not set, you can't check $_GET['p'] != 'index' and all the others. You'll have to check if it's set first:

<?php if(
    ! isset( $_GET['p'] ) ||
    ($_GET['p'] != 'index' &&
    $_GET['p'] != 'reg' &&
    $_GET['p'] != 'login' &&
    $_GET['p'] != 'ad')
): ?>

A better solution would be to put all those values in an array, and check if $_GET['p'] is in the array:

<?php if(
    ! isset( $_GET['p'] ) ||
    ! in_array(
        $_GET['p'],
        array('index', 'reg', 'login', 'ad')
    )
): ?>

EDIT:

Now that you provided some more info, here's what you should do:

if ( ! isset($_GET['p']) )
{
    // We're at the index page, so don't display anything
}
else
{
    if ( in_array( $_GET['p'], array('index', 'reg', 'login', 'ad') ) )
    {
        // Display your content window
    }
    else
    {
        // $_GET['p'] is not a valid value, display error
    }
}

edited Sep 25, 2011 at 19:14

answered Sep 25, 2011 at 18:44

Joseph Silber

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8 Comments

Simon Andersson Over a year ago

i copied your code straight from your comment and it still doesn't work, i even did arrays before and it just doesn't work, It does work when i check if the GET is a certain value, but not if it's not set at all

evilone Over a year ago

I don't understand - if you check if $_GET['p'] is null or empty, why you need other conditions to check values from that variable? If $_GET['p'] is null or empty then it doesn't contain values...

Joseph Silber Over a year ago

@evilone - As far as I understand the OP, this is what he's trying to do: If no value was passed as $_GET['p'], or $_GET['p'] is not equals to any of those values, then he glides through. Otherwise, he wants to issue an error.

Simon Andersson Over a year ago

I have a page where it checks if a $_GET is set with a certain value, for example if it's Hello then it displays a content window with the text "Hello". But i want nothing to be displayed on the Index, where no $_GET is set, and the Error page to be displayed when the $_GET value does not match any set value.

Simon Andersson Over a year ago

@JosephSilber Yeah. that is what i want.

|

SeanCannon · Accepted Answer · 2011-09-25 18:44:48Z

4

Your condition makes no sense. You're checking for 3 possible values of $_GET['p'] and then checking if $_GET['p'] is even set. Reverse your logic:

<?php
    if(isset($_GET['p']))
    {
        // display error page
    }
    else
    {
        // do something else
    }

answered Sep 25, 2011 at 18:44

SeanCannon

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Comments

evilone · Accepted Answer · 2011-09-25 19:19:22Z

2

You can check if $_GET['p'] is set by

if(isset($_GET['p']) {...}

If it's set and not empty then you can check for values that you need to check.

edited Sep 25, 2011 at 19:19

answered Sep 25, 2011 at 18:43

evilone

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2 Comments

Simon Andersson Over a year ago

i have tried !$_GET['p'], !isset, setting a variable when it's set, putting it in a different if statement both before And after the long list of if's, and Nothing seems to work.. the get looks like this in the address bar: ?p=index, and i just can't seem to get it to work

evilone Over a year ago

@albinlennstrand Are you sure that $_GET['p'] is empty when you think it's empty?

Alexey · Accepted Answer · 2011-09-25 18:50:19Z

0

Try this:

<?php 
$defaultvalue=0; // for example 0
$p=isset($_GET["p"]) ? $_GET["p"] : $defaultvalue;
if(($p != 'index') && ($p != 'reg') && ($p != 'login') && ($p != 'ad')): 
?>

answered Sep 25, 2011 at 18:50

Alexey

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1 Comment

Simon Andersson Over a year ago

worked just like the old script, it works if the certain values are set but not if it's not set at all :( i appreciate your help tho

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