zip and download files using php

Question

I am trying to zip and download files from a folder named \"upload\". Zip file is downloading but I couldn\'t open (extract) it. I am getting an error like \"The archive is eith

Answer 1

 $zip = new ZipArchive;
        if ($zip->open('assets/myzip.zip',  ZipArchive::CREATE)) {
            $zip->addFile('folder/bootstrap.js', 'bootstrap.js');
            $zip->addFile('folder/bootstrap.min.js', 'bootstrap.min.js');
            $zip->close();
            echo 'Archive created!';
            header('Content-disposition: attachment; filename=files.zip');
            header('Content-type: application/zip');
            readfile($tmp_file);
       } else {
           echo 'Failed!';
       }

I got this code to download files from a folder.