Files to a ZIP archive PHP

1. If you want to add files to a ZIP archive but you don't know if the ZiP file exists or not, you MUST check: this changes the way you open it !.
2. you can not append multiple flags, can use only one (or none).

If the zip does not exists, open it with:
$ziph->open($archiveFile, ZIPARCHIVE::CM_PKWARE_IMPLODE)
(or a different compression method)

If the zip already exists, open it with:
$ziph->open($archiveFile)
or
$ziph->open($archiveFile, ZIPARCHIVE::CHECKCONS)

Example: make backup files every hour and ZIP them all in a daily ZIP archive, so you want to get only one ZIP per day, each ZIP containing 24 files:

<?php
  function archivebackup($archiveFile, $file, &$errMsg)
  {
    $ziph = new ZipArchive();
    if(file_exists($archiveFile))
    {
      if($ziph->open($archiveFile, ZIPARCHIVE::CHECKCONS) !== TRUE)
      {
        $errMsg = "Unable to Open $archiveFile";
        return 1;
      }
    }
    else
    {
      if($ziph->open($archiveFile, ZIPARCHIVE::CM_PKWARE_IMPLODE) !== TRUE)
      {
        $errMsg = "Could not Create $archiveFile";
        return 1;
      }
    }
    if(!$ziph->addFile($file))
    {
      $errMsg = "error archiving $file in $archiveFile";
      return 2;
    }
    $ziph->close();
    
    return 0;
  }
?>