21段救命PHP代码(11)

        $short_string=myTruncate($long_string, 100, ' ');
　16. PHP文件 Zip 压缩
        /* creates a compressed zip file */
        function create_zip($files = array(),$destination = '',$overwrite = false) {
        //if the zip file already exists and overwrite is false, return false
        if(file_exists($destination) && !$overwrite) { return false; }
        //vars
        $valid_files = array();
        //if files were passed in...
        if(is_array($files)) {
        //cycle through each file
        foreach($files as $file) {
        //make sure the file exists
        if(file_exists($file)) {
        $valid_files[] = $file;
        }
        }
        }
        //if we have good files...
        if(count($valid_files)) {
        //create the archive
        $zip = new ZipArchive();
        if($zip->open($destination,$overwrite ? ZIPARCHIVE::OVERWRITE : ZIPARCHIVE::CREATE) !== true) {
        return false;
        }
        //add the files
        foreach($valid_files as $file) {
        $zip->addFile($file,$file);
        }
        //debug
        //echo 'The zip archive contains ',$zip->numFiles,' files with a status of ',$zip->status;   
        
        //close the zip -- done!
        $zip->close();   
        
        //check to make sure the file exists
        return file_exists($destination);
        }
        else
        {