PHP gets three functions for the suffix name of a file

Choose a good one to remember, later need to use the time can be used directly, or to this site to view this article can drop.

 
<?php 
// methods 1: 
function extend_1($file_name) 
{ 
$retval=""; 
$pt=strrpos($file_name, "."); 
if ($pt) $retval=substr($file_name, $pt+1, strlen($file_name) - $pt); 
return ($retval); 
} 

// methods 2 
function extend_2($file_name) 
{ 
$extend = pathinfo($file_name); 
$extend = strtolower($extend["extension"]); 
return $extend; 
} 

// methods 3 
function extend_3($file_name) 
{ 
$extend =explode("." , $file_name); 
$va=count($extend)-1; 
return $extend[$va]; 
} 
?>