php获取文件后缀6种方法

<?php
$filename = 'mypicname.jpg';
 
// 1. The "explode/end" approach
$ext = end(explode('.', $filename));
 
// 2. The "strrchr" approach
$ext = substr(strrchr($filename, '.'), 1);
 
// 3. The "strrpos" approach
$ext = substr($filename, strrpos($filename, '.') + 1);
 
// 4. The "preg_replace" approach
$ext = preg_replace('/^.*\.([^.]+)$/D', '$1', $filename);
 
// 5. The "never use this" approach
//   From: http://php.about.com/od/finishedphp1/qt/file_ext_PHP.htm
$exts = split("[/\\.]", $filename);
$n = count($exts)-1;
$ext = $exts[$n];
 
//6. The "pathinfo" approach
$ext = pathinfo($filename, PATHINFO_EXTENSION);
?>