Si vous avez besoin de détecter le navigateur ou le système d’exploitation de vos utilisateurs, voici le code !

// Simple browser and OS detection script. This will not work if User Agent is false.
$agent = $_SERVER['HTTP_USER_AGENT'];

// Detect Device/Operating System
if(preg_match('/Linux/i',$agent)) $os = 'Linux';
elseif(preg_match('/Mac/i',$agent)) $os = 'Mac'; 
elseif(preg_match('/iPhone/i',$agent)) $os = 'iPhone'; 
elseif(preg_match('/iPad/i',$agent)) $os = 'iPad'; 
elseif(preg_match('/Droid/i',$agent)) $os = 'Droid'; 
elseif(preg_match('/Unix/i',$agent)) $os = 'Unix'; 
elseif(preg_match('/Windows/i',$agent)) $os = 'Windows';
else $os = 'Unknown';

// Browser Detection
if(preg_match('/Firefox/i',$agent)) $br = 'Firefox'; 
elseif(preg_match('/Mac/i',$agent)) $br = 'Mac';
elseif(preg_match('/Chrome/i',$agent)) $br = 'Chrome'; 
elseif(preg_match('/Opera/i',$agent)) $br = 'Opera'; 
elseif(preg_match('/MSIE/i',$agent)) $br = 'IE'; 
else $bs = 'Unknown';

// Action when OS/Device is found
if($os=='Linux')  { echo 'This is done when the OS/Device is Linux'; }
if($os=='Mac')	  { echo 'This is done when the OS/Device is MacOS'; }
if($os=='iPhone') { echo 'This is done when the OS/Device is iPhone'; }
if($os=='iPad')   { echo 'This is done when the OS/Device is iPad'; }
if($os=='Droid')  { echo 'This is done when the OS/Device is Droid'; }
if($os=='Unix')   { echo 'This is done when the OS/Device is Unix'; }
if($os=='Unknown'){ echo 'This is done when the OS/Device is unknown. This is the failsafe for when an OS/Device is not detected.'; }

// Action when Browser is detected
if($br=='Firefox'){ echo 'This is done when the Browser is Firefox'; }
if($br=='Chrome') { echo 'This is done when the Browser is Chrome'; }
if($br=='Opera')  { echo 'This is done when the Browser is Opera'; }
if($br=='MSIE')   { echo 'This is done when the Browser is Microsoft Internet Explorer'; }
if($br=='Unknown'){ echo 'This is done when the Browser is Unknown. This is the failsafe for when a browser type is not detected'; }

// Action when both browser and OS/Device are detected
if($os=='Linux' && $br=='Firefox')  { echo 'This is done when the Browser is Firefox and the OS is Linux.'; }
if($os=='Unknown' && $br=='Unknown'){ echo 'This is done when the Browser is Unknown and the OS is Unknown. This is the catch-the-rest failsafe'; }

 

MISE A JOUR du 12 Février 2019 (merci à Sébastien pour ces fonctions)

3 fonctions beaucoup plus complète que mon code précédent

function detect_os() {
	$user_agent = $_SERVER['HTTP_USER_AGENT'];
	$browser        = "Inconnu";
	$browser_array = array( '/mobile/i'    => 'Handheld Browser',
				'/msie/i'      => 'Internet Explorer',
				'/trident/i'   => 'Internet Explorer',
				'/firefox/i'   => 'Firefox',
				'/safari/i'    => 'Safari',
				'/chrome/i'    => 'Chrome',
				'/edge/i'      => 'Edge',
				'/opera/i'     => 'Opera',
				'/netscape/i'  => 'Netscape',
				'/maxthon/i'   => 'Maxthon',
				'/konqueror/i' => 'Konqueror'
	);
	foreach ($browser_array as $regex => $value)
	if (preg_match($regex, $user_agent))
		$browser = $value;
	return $browser;
}
/**
 * Récupérer la véritable adresse IP d'un visiteur
 */
function get_ip() {
	// IP si internet partagé
	if (isset($_SERVER['HTTP_CLIENT_IP'])) {
		return $_SERVER['HTTP_CLIENT_IP'];
	}
	// IP derrière un proxy
	elseif (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
		return $_SERVER['HTTP_X_FORWARDED_FOR'];
	}
	// Sinon : IP normale
	else {
		return (isset($_SERVER['REMOTE_ADDR']) ? $_SERVER['REMOTE_ADDR'] : '');
	}
}
function detect_browser() {
	$user_agent = $_SERVER['HTTP_USER_AGENT'];
	$os_platform  = "Inconnu";
	$os_array     = array(  '/windows nt 10/i'      =>  'Windows 10',
				'/windows nt 6.3/i'     =>  'Windows 8.1',
				'/windows nt 6.2/i'     =>  'Windows 8',
				'/windows nt 6.1/i'     =>  'Windows 7',
				'/windows nt 6.0/i'     =>  'Windows Vista',
				'/windows nt 5.2/i'     =>  'Windows Server 2003/XP x64',
				'/windows nt 5.1/i'     =>  'Windows XP',
				'/windows xp/i'         =>  'Windows XP',
				'/windows nt 5.0/i'     =>  'Windows 2000',
				'/windows me/i'         =>  'Windows ME',
			 	'/win98/i'              =>  'Windows 98',
				'/win95/i'              =>  'Windows 95',
				'/win16/i'              =>  'Windows 3.11',
				'/macintosh|mac os x/i' =>  'Mac OS X',
				'/mac_powerpc/i'        =>  'Mac OS 9',
				'/linux/i'              =>  'Linux',
				'/ubuntu/i'             =>  'Ubuntu',
				'/iphone/i'             =>  'iPhone',
				'/ipod/i'               =>  'iPod',
				'/ipad/i'               =>  'iPad',
				'/android/i'            =>  'Android',
				'/blackberry/i'         =>  'BlackBerry',
				'/webos/i'              =>  'Mobile'
	);
	foreach ($os_array as $regex => $value)
	if (preg_match($regex, $user_agent))
		$os_platform = $value;
	return $os_platform;
}
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