function extend_1($file_name) 
{ 
$retval=""; 
$pt=strrpos($file_name, "."); 
if ($pt) $retval=substr($file_name, $pt+1, strlen($file_name) - $pt); 
return ($retval); 
} 

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

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