PHP Redirect w/ Arrays (Not working?)

Question

I made a redirect script as listed below... no matter what value of p is passed, even if valid, it is redirected to the default.htm page... essentially it is skipping the if/else part and always going to the else.

Is there something special about the php header function where it is disregarding the conditional statements?

<?php

/*
Use the following link format:
<a href="goto.php?p=XXXXXX">XXXXXX</a>
*/

$p = $_GET['p'];
$link = array(

/*Links*/
'link1'=>'/link1.htm',
'link2'=>'/link2.htm',

);

/*Send Headers*/

header('Content-Type: text/html; charset=utf-8');
header('X-Robots-Tag: noindex, nofollow, noarchive', true);

if (in_array($p, $link))
{
    header('Location: '.$link[$p]); // Valid p
}  
else
{
    header('Location: /default.htm'); // Invalid p
}

exit();
?>

Instead of redirecting comment it out and var_dump(in_array($p,$link)) and see if you're getting true or false. If false, you know there's something going on with your $_GET['p'] and/or $link definition. — Jeff
– Jeff, Commented Oct 6, 2012 at 18:56

user1725612 · Accepted Answer · 2012-10-06 19:02:43Z

3

use array_key_exists some what like this

if ((array_key_exists('p', $_GET) && isset($link[$p]))
{
    header('Location: '.$link[$p]); // Valid p
}  
else
{
    header('Location: /default.htm'); // Invalid p
}

The above worked for me and also it wont show index undefined warning since you use array_key exists

answered Oct 6, 2012 at 19:02

user1725612

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1 Comment

user756659 Over a year ago

I had to change to if (array_key_exists('p', $_GET) && isset($link[$p])) - removed an extra (, but this worked perfectly fine... thank you soo much

hakre · Accepted Answer · 2012-10-06 19:06:40Z

1

Instead of:

if (in_array($p, $link))

you want:

if (array_key_exists($p, $link))

The first checks against the values (right of the =>s). The second checks against the keys (left of the =>s).

See: http://php.net/manual/en/function.array-key-exists.php

The short version in your case is:

$link = @$link[$p] ?: '/default.htm';
header("Location: $link");

Which spares you the if and else.

edited Oct 6, 2012 at 19:06

hakre

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answered Oct 6, 2012 at 18:59

dkamins

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1 Comment

user756659 Over a year ago

Tried this and the result was a redirect to /$link no matter what value of p is sent.

newfurniturey · Accepted Answer · 2012-10-06 19:11:05Z

0

You're checking if the value of $_GET['p'] is in the values-list of $link, but then you're using it as the key in the header() call. It looks like you mean to if $_GET['p'] is a key in the $link array.

To do this, use isset() instead of in_array() to check the array's keys (in_array() will check the array's values):

if (isset($link[$p])) {
    header('Location: '.$link[$p]); // Valid p
}

edited Oct 6, 2012 at 19:11

answered Oct 6, 2012 at 18:56

newfurniturey

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4 Comments

jeremy Over a year ago

array_key_exists is probably better then isset here

newfurniturey Over a year ago

@Nile Personally, I think array_key_exists() is just a convenience-method for isset(). Also, per benchmark testing, isset() is a lot faster. I haven't confirmed, but I believe that they perform the same low-end tests to check for being set.

jeremy Over a year ago

according to this, you should use both in case of that weird null case

newfurniturey Over a year ago

@Nile The weird null case is what's experienced by inexperienced programmers; the documentation for isset() specifically says it returns false on null - that's why we use it. Also, it's perfectly applicable to the OP's question (so is using array_key_exists(); they both will perform the same task in this case)

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