Regex within a switch Question

[mrwilson]

I have a simple script, in which I am trying to pull the browser type out of an agent string. This should be horribly easy but I cant seem to pull it off.

I am using regex, and have tried a dizzying array of different configurations. The only response I am getting from the script is the default case, that being unknown. In using my own user agent string, I know the word Firefox is within the string but cant capture it.

$agent = $_SERVER["HTTP_USER_AGENT"];

if (isset($agent)){
switch($agent){
    case 1:
    if (preg_match('/(?:MSIE 3)/', $agent)){
        $browser = "MSIE 3";
        
    }break;
    case 2:
    if (preg_match('/(?:MSIE 4)/', $agent)){
        $browser = "MSIE 4";
        
    }break;
    case 3:
    if (preg_match('/(?:MSIE 5)/', $agent)){
        $browser = "MSIE 5";
       
    } break;
    case 4:
    if (preg_match('/(?:MSIE 6)/', $agent)){
        $browser = "MSIE 6";
        
    }break;
    case 5:
    if (preg_match('/(?:MSIE 7)/', $agent)){
        $browser = "MSIE 7";
        
    }break;
    case 6:
    if (preg_match('/?:(MSIE 8)/', $agent)){
        $browser = "MSIE 8";
     
    } break;
    case 7:
    if (preg_match('/(?:Opera)/', $agent)){
        $browser = "Opera";
        
    }break;
    case 8:
    if (preg_match('/(?:Chrome)/', $agent)){
        $browser = "Chrome";
        
    }break;
    case 9:
    if (preg_match('/(?:Safari)/', $agent)){
        $browser = "Safari";
        
    }break;
    case 10:
    if (preg_match('/^(?:(Firefox))$/', $agent)){
        $browser = "Firefox";        
    }break;
          
    default:
    $browser = "Unknown"; 
}
}

I have tried the break within the if statement and outside. The script from here just goes on to enter the browser into the database.

Any thoughts?

[NogDog]

Looks like a misunderstanding of the "case" part of a switch(). case 1: is testing if $agent == 1. Since it does not, it goes to the next case, and so on until you reach the default. Also, you don't want to anchor the "Firefox" to the start (^) and end ($) of the regexp. Lastly, by definition $agent is always set since you define it right before you do the isset(). So, here's a shortened piece of code that correctly identified by Firefox browser string:

<?php
$agent = $_SERVER["HTTP_USER_AGENT"];
switch (1) {
    case preg_match('/MSIE 3/', $agent):
        $browser = "MSIE 3";
        break;
    
    case preg_match('/Firefox/', $agent):
        $browser = "Firefox";
        break;
    
    default:
        $browser = "Unknown";
}
echo $browser;

[mrwilson]

Ah I see, thank you very much nogdog, as usual you are very helpful. I understand what I was doing wrong

[NogDog]

PS: I might approach it from this direction, both as less code and ease of maintenance (just have to change the array to change the list of browsers):

<?php
$agent = $_SERVER["HTTP_USER_AGENT"];
$browsers = array(
   'MSIE 3',
   'MSIE 4',
   'MSIE 5',
   'MSIE 6',
   'MSIE 7',
   'MSIE 8',
   'Chrome',
   'Safari',
   'Opera',
   'Firefox'
);
$regexp = '/' . implode('|', $browsers) . '/';
$browser = preg_match($regexp, $agent, $matches) ? $matches[0] : 'unknown';
echo $browser;

[mrwilson]

That makes a lot of sense, I will give that a try