//方法一:
function extend_1($file_name)
{
? $retval=;
? $pt=strrpos($file_name, .);
? if ($pt) $retval=substr($file_name, $pt+1, strlen($file_name) - $pt);
? return ($retval);
}
//方法二
function extend_2($file_name)
{
? $extend = pathinfo($file_name);
? $extend = strtolower($extend[extension]);
? return $extend;
}
//方法三
function extend_3($file_name)
{
? $extend =explode(. , $file_name);
? return $extend[1];
}
$file = c:\test.test\haha.haha.txt;
echo extend_1($file);
echo \n
\n;
echo extend_2($file);
echo \n
\n;
echo extend_3($file);
?>
返回结果：
txt
txt
test\haha
=============================================================
$file = a.b.c.jpeg;
$ext = strrchr($file, .);
print $ext;