Código PHP:
<?php //upload directory.
//change to fit your need eg. files, upload .... etc.
$upload_dir = "images/";
//number of files to upload.
$num_files = 5;
//the file size in bytes.
$size_bytes =51200; //51200 bytes = 50KB.
//Extensions you want files uploaded limited to.
$limitedext = array(".gif",".jpg",".jpeg",".png",".txt",".nfo",".doc",".rtf",".htm",".dmg",".zip",".rar",".gz",".exe",".pdf");
//check if the directory exists or not.
if (!is_dir("$upload_dir")) {
die ("Error: The directory <b>($upload_dir)</b> doesn't exist");
}
//check if the directory is writable.
if (!is_writeable("$upload_dir")){
die ("Error: The directory <b>($upload_dir)</b> is NOT writable, Please CHMOD (777)");
}
//if the form has been submitted, then do the upload process
//infact, if you clicked on (Upload Now!) button.
if (isset($_POST['upload_form'])){
echo "<h3>Upload results:</h3>";
//do a loop for uploading files based on ($num_files) number of files.
for ($i = 1; $i <= $num_files; $i++) {
//define variables to hold the values.
$new_file = $_FILES['file'.$i];
$file_name = $new_file['name'];
//to remove spaces from file name we have to replace it with "_".
$file_name = str_replace(' ', '_', $file_name);
$file_tmp = $new_file['tmp_name'];
$file_size = $new_file['size'];
#-----------------------------------------------------------#
# this code will check if the files was selected or not. #
#-----------------------------------------------------------#
if (!is_uploaded_file($file_tmp)) {
//print error message and file number.
echo "File $i: Not selected.<br>";
}else{
#-----------------------------------------------------------#
# this code will check file extension #
#-----------------------------------------------------------#
$ext = strrchr($file_name,'.');
if (!in_array(strtolower($ext),$limitedext)) {
echo "File $i: ($file_name) Wrong file extension. <br>";
}else{
#-----------------------------------------------------------#
# this code will check file size is correct #
#-----------------------------------------------------------#
if ($file_size > $size_bytes){
echo "File $i: ($file_name) Faild to upload. File must be <b>". $size_bytes / 1024 ."</b> KB. <br>";
}else{
#-----------------------------------------------------------#
# this code check if file is Already EXISTS. #
#-----------------------------------------------------------#
if(file_exists($upload_dir.$file_name)){
echo "File $i: ($file_name) already exists.<br>";
}else{
#-----------------------------------------------------------#
# this function will upload the files. :) ;) cool #
#-----------------------------------------------------------#
if (move_uploaded_file($file_tmp,$upload_dir.$file_name)) {
echo "File $i: ($file_name) Uploaded.<br>";
}else{
echo "File $i: Faild to upload.<br>";
}#end of (move_uploaded_file).
}#end of (file_exists).
}#end of (file_size).
}#end of (limitedext).
}#end of (!is_uploaded_file).
}#end of (for loop).
# print back button.
echo "»<a href=\"$_SERVER[PHP_SELF]\">back</a>";
////////////////////////////////////////////////////////////////////////////////
//else if the form didn't submitted then show it.
}else{
echo " <h3>Select files to upload!.</h3>
Max file size = ". $size_bytes / 1024 ." KB";
echo " <form method=\"post\" action=\"$_SERVER[PHP_SELF]\" enctype=\"multipart/form-data\">";
// show the file input field based on($num_files).
for ($i = 1; $i <= $num_files; $i++) {
echo "File $i: <input type=\"file\" name=\"file". $i ."\"><br>";
}
echo " <input type=\"hidden\" name=\"MAX_FILE_SIZE\" value=\"$size_bytes\">
<input type=\"submit\" name=\"upload_form\" value=\"Upload Now!\">
</form>";
}
//print copyright ;-)
echo"<p align=\"right\"><br>Script by: <a href=\"http://www.maaking.com\">maaking.com</a></p>";
?> 
