在网上查到的不好用，简单修改一下.....嘿嘿！

<?php
$code_file     = 'coded.txt'; //加密后文件
$decode_file     = 'decoded.txt'; //解密后代码存放文件

echo '<pre>';
echo "\nDECODE nested eval(gzinflate()) by DEBO Jurgen AND modify By jayeeliu\r\n";
echo "1. Reading coded file\n";
$contents = file_get_contents($code_file);
echo "2. Decoding\n";
$i=1;
while (preg_match("/eval[ ]*\([ ]*gzinflate/",$contents)) {//在eval(的'('两边加入多空格匹配
    echo $i++."\r\n";//显示解密次数
    $contents=preg_replace("/<\?php|\?>/", "", $contents);
    $contents=preg_replace("/<\?|\?>/", "", $contents);
     
    eval(preg_replace("/eval/", "\$contents=", $contents));
}
$contents = substr(substr($contents, 2), 0, -2);//去除开始的\?\>(\只是转义，文件中没有)和结尾的<?
echo "3. Writing decoded file\n";
echo file_put_contents($decode_file, $contents);
echo '</pre>';
?>