How to detect Internet Explorer with PHP

abstract

It is possible to use PHP to check whether your site visitor uses Internet Explorer and output some IE-specific text or HTML/CSS markup .

compatible

PHP 4.1.0 or newer

In PHP superglobal array $_SERVER there is usually HTTP_USER_AGENT element which contains browser-specific id string

Internet Explorer uses something like

Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)"

as id-string, depending on platform and version. Every version of IE has "MSIE" part in HTTP_USER_AGENT string, so it is possible to detect IE simply by scanning $_SERVER['HTTP_USER_AGENT'] for string "MSIE".

Example: function ae_detect_ie below returns true if Internet Explorer has been detected.

<?php
function ae_detect_ie()
{
    if (isset($_SERVER['HTTP_USER_AGENT']) && 
    (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE') !== false))
        return true;
    else
        return false;
}
?>

For a maximum speed, we use strpos function instead of strstr, preg_match or other PHP string-search functions. Note, that if you want to check for IE in several places, it is better to store function value in some variable, to avoid serveral similar string-searches.

Here is the example of detecting Internet Explorer and suggesting user to get another browser:

<!-- function ae_detect_ie (see code above) is pasted here  -->
<?php  if (ae_detect_ie()) {  ?>
It seems, that your are using MSIE.
Why not to switch to standard-complaint brower, like 
<a href="http://www.mozilla.com/firefox/">Firefox</a>?
<?php }  ?>

tested by AnyExample.com on 2006-07-30

PHP 5.0.5 :: Microsoft Internet Explorer 6.0
PHP 5.0.5 :: Firefox 1.5

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