Multiple files can be uploaded using different name for input.
It is also possible to upload multiple files simultaneously and have the information organized automatically in arrays for you. To do so, you need to use the same array submission syntax in the HTML form as you do with multiple selects and checkboxes:
Example #1 Uploading multiple files
<form action="file-upload.php" method="post" enctype="multipart/form-data"> Send these files:<br /> <input name="userfile" type="file" /><br /> <input name="userfile" type="file" /><br /> <input type="submit" value="Send files" /> </form>
When the above form is submitted, the arrays $_FILES['userfile'], $_FILES['userfile']['name'], and $_FILES['userfile']['size'] will be initialized (as well as in $HTTP_POST_FILES for PHP versions prior to 4.1.0). When register_globals is on, globals for uploaded files are also initialized. Each of these will be a numerically indexed array of the appropriate values for the submitted files.
For instance, assume that the filenames /home/test/review and /home/test/xwp.out are submitted. In this case, $_FILES['userfile']['name'] would contain the value review, and $_FILES['userfile']['name'] would contain the value xwp.out. Similarly, $_FILES['userfile']['size'] would contain review's file size, and so forth.
Since PHP 5.2.12, the max_file_uploads configuration setting acts as a limit on the number of files that can be uploaded in one request. You will need to ensure that your form does not try to upload more files in one request than this limit.