<?php
$file = "/home/lvyaozu/backup_20080115.txt";

for($i=1; $i < 6; $i++) {
$func = 'get_file_ext_' . $i;
var_dump($func($file));
}


function get_file_ext_1($file) {
return strtolower(trim(substr(strrchr($file, '.'), 1)));
}

function get_file_ext_2($file) {
return strtolower(trim(pathinfo($file, PATHINFO_EXTENSION)));
}

function get_file_ext_3($file) {
return strtolower(trim(substr($file, strrpos($file, '.')+1)));
}

function get_file_ext_4($file) {
return strtolower(trim(array_pop(explode('.', $file))));
}

function get_file_ext_5($file) {
$tok = strtok($file, '.');
while($tok !== false) {
$return = $tok;
$tok = strtok('.');
}
return strtolower(trim($return));
}
?>

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/lvyaozu/archive/2009/06/03/4237628.aspx