preg_match_all( '#(?<browser>' . join('|', array('msie', 'firefox', 'safari', 'webkit', 'opera', 'netscape', 'konqueror', 'gecko')).')[/ ]+(?<version>[0-9]+(?:\.[0-9]+)?)#', strtolower($_SERVER['HTTP_USER_AGENT']), $gear_browser);

function ObtenerNavegador($user_agent) {
     $navegadores = array(
          'Opera' => 'Opera',
          'Mozilla Firefox'=> '(Firebird)|(Firefox)',
          'Galeon' => 'Galeon',
          'Mozilla'=>'Gecko',
          'MyIE'=>'MyIE',
          'Lynx' => 'Lynx',
          'Netscape' => '(Mozilla/4\.75)|(Netscape6)|(Mozilla/4\.08)|(Mozilla/4\.5)|(Mozilla/4\.6)|(Mozilla/4\.79)',
          'Konqueror'=>'Konqueror',
          'Internet Explorer 7' => '(MSIE 7\.[0-9]+)',
          'Internet Explorer 6' => '(MSIE 6\.[0-9]+)',
          'Internet Explorer 5' => '(MSIE 5\.[0-9]+)',
          'Internet Explorer 4' => '(MSIE 4\.[0-9]+)',
);
foreach($navegadores as $navegador=>$pattern){
       if (eregi($pattern, $user_agent))
       return $navegador;
    }
return 'Desconocido';
}
?>
 
...
 
<?php echo ObtenerNavegador($_SERVER['HTTP_USER_AGENT']) ?>
 

 if (eregi($pattern, $user_agent))
 

<script language="javascript">
	//detección del navegador
	var BrowserDetect = {
		   init: function () {
			  this.browser = this.searchString(this.dataBrowser) || "unknown";
			  this.version = this.searchVersion(navigator.userAgent) || this.searchVersion(navigator.appVersion) || "unknown";
			  this.OS = this.searchString(this.dataOS) || "an unknown OS";
		   },
		searchString: function (data) {
		   for (var i=0;i<data.length;i++) {
			  var dataString = data[i].string;
			  var dataProp = data[i].prop;
			  this.versionSearchString = data[i].versionSearch || data[i].identity;
			  if (dataString) {
				 if (dataString.indexOf(data[i].subString) != -1)
					return data[i].identity;
			  }
			  else if (dataProp)
			  return data[i].identity;
		   }
		},
		searchVersion: function (dataString) {
		   var index = dataString.indexOf(this.versionSearchString);
		   if (index == -1) return;
		   return parseFloat(dataString.substring(index+this.versionSearchString.length+1));
		},
		dataBrowser: [
		{
		   string: navigator.vendor,
		   subString: "Apple",
		   identity: "Safari"
		},
		{
		   prop: window.opera,
		   identity: "Opera"
		},
		{
		   string: navigator.vendor,
		   subString: "iCab",
		   identity: "iCab"
		},
		{
		   string: navigator.vendor,
		   subString: "KDE",
		   identity: "Konqueror"
		},
		{
		   string: navigator.userAgent,
		   subString: "Firefox",
		   identity: "Firefox"
		},
		{
		   string: navigator.vendor,
		   subString: "Camino",
		   identity: "Camino"
		},
		{ // for newer Netscapes (6+)
		   string: navigator.userAgent,
		   subString: "Netscape",
		   identity: "Netscape"
		},
		{
		   string: navigator.userAgent,
		   subString: "MSIE",
		   identity: "Explorer",
		   versionSearch: "MSIE"
		},
		{
		   //esta parte reconoce el chrome
		   string: navigator.userAgent,
		   subString: "Gecko",
		   identity: "Chrome", //Mozilla
		   versionSearch: "rv"
		},
		{ // for older Netscapes (4-)
		   string: navigator.userAgent,
		   subString: "Mozilla",
		   identity: "Netscape",
		   versionSearch: "Mozilla"
		}
		],
		dataOS : [
		{
		   string: navigator.platform,
		   subString: "Win",
		   identity: "Windows"
		},
		{
		   string: navigator.platform,
		   subString: "Mac",
		   identity: "Mac"
		},
		{
		   string: navigator.platform,
		   subString: "Linux",
		   identity: "Linux"
		}
	]
 
	};
	BrowserDetect.init();
 
	//estilos de cada navegador
	if (BrowserDetect.browser == "Firefox") {
		document.write("<LINK REL='stylesheet' HREF='../css/content.css' TYPE='text/css'>");
	} else {
 
		if (BrowserDetect.browser == "Explorer"){
			   if (BrowserDetect.version>=7){
				  document.write("<LINK REL='stylesheet' HREF='../css/ie7.css' TYPE='text/css'>");
			   }
		} else {
 
			if (BrowserDetect.browser == "Opera"){
					  if (BrowserDetect.version<9){
						 document.write("<LINK REL='stylesheet' HREF='../css/opera.css' TYPE='text/css'>");
					  }else{
						 document.write("<LINK REL='stylesheet' HREF='../css/opera9.css' TYPE='text/css'>");
					  }
			} else {
 
				if (BrowserDetect.browser == "Safari"){
							 document.write("<LINK REL='stylesheet' HREF='../css/safari.css' TYPE='text/css'>");
				}else{
							 document.write("<LINK REL='stylesheet' HREF='../css/chrome.css' TYPE='text/css'>");
				}
			}
		}
	}
 
	</script> 
 

<?php 
    session_start(); 
        function cookie(){ 
            setcookie("mail", $_POST['mail'], time()+3600); 
            setcookie("pass", $_POST['pass'], time()+3600);
        }
        if($_POST['mail']!=' '||$_POST['pass']!=' '){
        cookie();
        }
?>

$comprueba=mysql_query("Select alias,mail,pass from usuarios where mail = '".$_COOKIE['mail']."' && pass=MD5('".$_COOKIE['pass']."')");
 
$nick = mysql_fetch_array(mysql_query("Select alias,mail,pass from usuarios where mail = '".$_COOKIE['mail']."' && pass = MD5('".$_COOKIE['pass']."')"));

<table>
<td >
<img id="carpeta" alt="Boton Examinar" src="../img/carpeta.jpeg"  onclick="document.getElementById('btnexaminar').click()" /></td>
<!-- contenido carpeta/docs -->
<form action='' method='post' enctype='multipart/form-data'></td><tr>
 
<td style="display: none;"><input name='archivo' type='file' id='btnexaminar' class='oculto' size='35' /></td><tr>
 
<td style="display: ;" id="subir"><input name="enviar" id="boton-enviar" type="submit" value="Subir" /></td><tr>
 
<td><input name="action" id="action-enviar" type="hidden" value="upload" />
<td>
<script type="text/javascript">
var contenido = getElementByName("archivo");
</script>
</td><tr>
 </form>
  </td><tr>
 <!-- fin contenido carpeta/docs -->
<td></td><td></td><tr>
</table>
 

<style>#btnexaminar {display:none}</style>
<form action='upload.php' method='post' enctype='multipart/form-data'></td><tr>
                                     <td><input name='archivo' type='file' id='btnexaminar' class='oculto' size='35' /></td><tr>
                                     <td id="subir"><input name="enviar" id="boton-enviar" type="submit" value="Subir" /></td><tr>
                                     <td><input name="action" type="hidden" value="upload" />
 
 

 
<form action="upload.php" method="post" enctype="multipart/form-data">
<input name="archivo" type="file" size="35" />
<input name="enviar" type="submit" value="Subir" />
<input name="action" type="hidden" value="upload" />     
</form>
 
 

echo"<script language='javascript'>window.location='../index.php';</script>;";
 

<?php 
session_start();
    $conectarbd= mysql_connect( "localhost", "root", "");
	if($conectarbd){
		$conectar_tabla= mysql_select_db("bag");
		if($conectar_tabla){
          $comprueba=mysql_query("Select alias,mail,pass from usuarios where mail = '".$_POST['mail']."' && pass='".$_POST['pass']."'");
          if($comprueba){
            $nick = mysql_fetch_array(mysql_query("Select alias,mail,pass from usuarios where mail = '".$_POST['mail']."' && pass = '".$_POST['pass']."'"));
            $_SESSION['nick']= $nick[0];
            if($_SESSION['nick']!= ""){
                echo "<p> ".$nick[0]." </p>";
            }else{
                header("Location: ../index.html");
            }
          }
        }
    }
session_destroy();
?>
 

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at C:\xampp\htdocs\projecte\pag\content.php:153) in C:\xampp\htdocs\projecte\pag\content.php on line 154

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at C:\xampp\htdocs\projecte\pag\content.php:153) in C:\xampp\htdocs\projecte\pag\content.php on line 154