<?php
function unzip($file,$dir=rand(10000,99999)){
      $path=realpath($file);
      $path=dirname($path);
      $zip = new ZipArchive() ;
      if ($zip->open($file) !== TRUE) {
        die ('Could not open archive');
      }
        if(!is_dir($dir)){
            die("Dir $dir does not exist");
        }
        $zip->extractTo("$path");
        $zip->close();
}
?> 

<?
    unzip("file.zip","folder");
?>