PHP如何判断用户浏览器类型

[asp]代码库

<?php
if(strpos($_SERVER["HTTP_USER_AGENT"],"MSIE 8.0"))  
echo "Internet Explorer 8.0";  
else if(strpos($_SERVER["HTTP_USER_AGENT"],"MSIE 7.0"))  
echo "Internet Explorer 7.0";  
else if(strpos($_SERVER["HTTP_USER_AGENT"],"MSIE 6.0"))  
echo "Internet Explorer 6.0";  
else if(strpos($_SERVER["HTTP_USER_AGENT"],"Firefox/3"))  
echo "Firefox 3";  
else if(strpos($_SERVER["HTTP_USER_AGENT"],"Firefox/2"))  
echo "Firefox 2";  
else if(strpos($_SERVER["HTTP_USER_AGENT"],"Chrome"))  
echo "Google Chrome";  
else if(strpos($_SERVER["HTTP_USER_AGENT"],"Safari"))  
echo "Safari";  
else if(strpos($_SERVER["HTTP_USER_AGENT"],"Opera"))  
echo "Opera";  
else echo $_SERVER["HTTP_USER_AGENT"];  
?>