PHP: rename multiple image before uploading - php

Question

is their any way to modify this code
<?php
$desired_dir= ($_SERVER['DOCUMENT_ROOT']).'/cert/uploads/';
if(isset($_FILES['files'])){
$cat_name='image/*';
if($cat_name==""){
echo "Category Required";
/*header('Refresh: 1;url=addfile.php');*/
}
else{
$count=0;
foreach($_FILES['files']['tmp_name'] as $key => $tmp_name ){
$file_name = $key.$_FILES['files']['name'][$key];
$size =$_FILES['files']['size'][$key];
$file_f = $size / 1024;
$file_size =round($file_f);
$file_tmp =$_FILES['files']['tmp_name'][$key];
$file_type=$_FILES['files']['type'][$key];
$path="uploads/";
if($size==0){
echo "<h6 style='color:red'>$file_name Exeeds upload limit</h6>";
}
else{
if (file_exists("$desired_dir" . $file_name))
{
echo "<h6 style='color:red'>".$file_name . " already exists.</h6>";
}
else
{
$query="INSERT into tblphotos VALUES('','$file_name')";
if(mysqli_query($con, $query)){
move_uploaded_file($file_tmp,"$desired_dir".$file_name);
//echo "<p style='color:blue'>$file_name Uploaded</p";
$count=$count+1;
}
else{
echo "Error in adding Files";
}
}
}
}
echo "<h6 style='color:blue'>"."$count Files Uploaded<h6>";
/*header('Refresh: 2;url=addfile.php');*/
}
}
?>
to change the name of every image i upload. for example i have a $id = 1 in my scipt
i want the combination of the id and the arrays to be its name just like example below.
1_[0].jpg, 1_[1].jpg, 1_[2].jpg
Thank You

Answer 1

if you already have $id = 1
Then try this :
$file_name = $id.'['. $key.$_FILES['files']['name'][$key] . ']';