php获取文件后缀名的几种方法

<?php

function getExt($filename) {

//strrpos()函数查找字符串在另一个字符串中最后一次出现的位置。如果成功，则返回位置，否则返回 false。

$ext = strtolower ( substr ( $filename, strrpos ( $filename, '.' ) + 1 ) );

return $ext;

}

function getExt1($filename) {

//strrev()函数反转字符串

$str = strrev ( $filename );

$ext = strrev ( strtolower ( substr ( $str, 0, strpos ( $str, '.' ) ) ) );

return $ext;

}

function getExt2($filename) {

$ext = substr ( strrchr ( $filename, '.' ), 1 );

return $ext;

}

function getExt3($filename) {

$arr = explode ( '.', $filename );

$ext = strtolower ( end ( $arr ) );

return $ext;

}

function getExt4($filename) {

//array_reverse — 返回一个单元顺序相反的数组 explode() 字符分割

$arr = array_reverse ( explode ( '.', $filename ) );

$ext = strtolower ( $arr [0] );

return $ext;

}

function getExt5($filename) {

//split — 用正则表达式将字符串分割到数组中

$arr = split ( "\.", $filename );

$ext = strtolower ( array_pop ( $arr ) );

return $ext;

}

function getExt6($filename) {

$ext = strtolower ( pathinfo ( $filename, PATHINFO_EXTENSION ) );

return $ext;

}

function getExt7($filename) {

//pathinfo — 返回文件路径的信息

$arr = pathinfo ( $filename );

$ext = strtolower ( $arr ['extension'] );

return $ext;

}

function getExt8($filename) {

//preg_split — 用正则表达式分割字符串

$arr = preg_split ( '/\./', $filename );

$ext = strtolower ( $arr [count ( $arr ) - 1] );

return $ext;

}