php redirect doesn't work properly

Question

I got a simple redirect on my homepage, which reacts to the user being on a smartphone or tablett. The Class is working and gives back a true when the side is opened on a smartphone.

Therefore if i write an echo in the if-statement it gets echoed. But the redirection doesn't work and i can't make a sense of it. Anyone any clue what i missed here?

include ('includes/Mobiledetecter.php');                 
$detect = new Mobiledetecter;                                  
                                 //
if($detect->isMobile() or $detect->isTablet()) {           
    header('Location: http://www.example.com/');
}

You're not, by any chance, outputting anything before the header() are you? stackoverflow.com/questions/8028957/… — CD001
– CD001, Commented Jul 19, 2016 at 14:28
Headers come before body. That's the rule. A redirect header means the client doesn't see anything intermediate. — apokryfos
– apokryfos, Commented Jul 19, 2016 at 14:30

BeetleJuice · Accepted Answer · 2016-07-19 14:37:11Z

6

Exit immediately after setting the header if there is nothing else to do:

if($detect->isMobile() or $detect->isTablet()) {           
    header('Location: http://www.example.com/');
    exit;
}

Also consider that headers only work if you haven't already sent output to the browser, either explicitly (eg: echo) or implicitly (eg: by having anything including blank space before the <?php tag that contains this header)

edited Jul 19, 2016 at 14:37

answered Jul 19, 2016 at 14:30

BeetleJuice

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1 Comment

Poiz Over a year ago

One up for the Zen Master as well ;-)

Poiz · Accepted Answer · 2016-07-19 14:31:50Z

2

Make sure your code is right at the very top of your Script before any output and also that your opening php tags has no white-space character(s) before it. In essence, your script should look something like this:

<?php // NOTICE THAT THERE IS NO SPACE BEFORE <?php & NO ECHO BEFORE header(...)

    include ('includes/Mobiledetecter.php');                 
    $detect = new Mobiledetecter;                                  
                             //
    if($detect->isMobile() or $detect->isTablet()) {           
        header("Location: http://www.example.com/");
        exit;
    }

answered Jul 19, 2016 at 14:31

Poiz

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3 Comments

BeetleJuice Over a year ago

upvote: good thinking with the space before <?php. It's such an easy mistake to make and such a hard bug to fix if you don't know about this rule.

Poiz Over a year ago

@BeetleJuice It may sound somehow strange to hear this but honestly, you are a very sincere & straightforward person... just an observation from about 2 - 3 encounters with you so far... and thanks a lot for the up-vote plus commendation ;-)

BeetleJuice Over a year ago

Much appreciated. <<tip of the hat>>

apokryfos · Accepted Answer · 2016-07-19 14:34:05Z

1

Further to what everyone else is correctly saying that you can't both echo and do a server-side redirect, here's a way to say something and then redirect:

include ('includes/Mobiledetecter.php');                 
$detect = new Mobiledetecter;                                  
                                 //
if($detect->isMobile() or $detect->isTablet()) {           
     echo "Redirecting you to the example website";
     echo "Click <a href='http://www.example.com/'>here</a> if you are not redirected within 5 seconds";        
     echo "<script> setTimeout(function () { window.location.href='http://www.example.com/'; }, 3000);</script>"
     exit;
}

answered Jul 19, 2016 at 14:34

apokryfos

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1 Comment

BeetleJuice Over a year ago

That's creative :-)

Lionnel · Accepted Answer · 2016-07-19 14:39:23Z

1

Try ob_end_clean function before header : http://php.net/manual/fr/function.ob-end-clean.php

answered Jul 19, 2016 at 14:39

Lionnel

175 bronze badges

1 Comment

BeetleJuice Over a year ago

If output buffering is on, the header will be set properly without the need for this function (just tested this). If output buffering is off, this function won't fix the output problem because there would be no buffer to clean. So I don't know what circumstance this function actually improves. Am I misunderstanding it?

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