将目录下所有文件替换成jpg格式

rename.php

<?php
$dir = opendir("images");
$dirname = dirname(__FILE__) . '\images';
echo $dirname;
while(($file = readdir($dir)) !== false) {
    if ($file!='.' and $file!='..') {
        echo "filename: {$file}\n";
        $newFilename = substr_replace($file, 'jpg', -3, 3);
        rename($dirname . "\\" . $file, $dirname . "\\" . $newFilename);
    }
}
closedir();