分割大文件和合并文件的源代码

 0) {
        $cacheFile = $cacheFileName . $num++ . '.dat';
        if (file_exists($cacheFile)) {
            $cfile = fopen($cacheFile, 'rb');
            $content = fread($cfile, filesize($cacheFile));
            fclose($cfile);
            fwrite($file, $content);
        } else {
            $num = -1;
        }
    }
    fclose($file);    
}