PHP - Switch() Inside Preg_replace

$desired_width = 110;

if (isset($_POST['submit'])) {
    $j = 0; //Variable for indexing uploaded image

    for ($i = 0; $i < count($_FILES['file']['name']); $i++) {//loop to get individual element from the array
        $target_path = $_SERVER['DOCUMENT_ROOT'] . "/gallerysite/multiple_image_upload/uploads/"; //Declaring Path for uploaded images

        $validextensions = array("jpeg", "jpg", "png");  //Extensions which are allowed
        $ext = explode('.', basename($_FILES['file']['name'][$i]));//explode file name from dot(.) 
        $file_extension = end($ext); //store extensions in the variable

        $new_image_name = md5(uniqid()) . "." . $ext[count($ext) - 1];
		$target_path = $target_path . $new_image_name;//set the target path with a new name of image
        $j = $j + 1;//increment the number of uploaded images according to the files in array       
      
	  if (($_FILES["file"]["size"][$i] < 100000) //Approx. 100kb files can be uploaded.
                && in_array($file_extension, $validextensions)) {
            if (move_uploaded_file($_FILES['file']['tmp_name'][$i], $target_path)) {//if file moved to uploads folder
                echo $j. ').<span id="noerror">Image uploaded successfully!.</span><br/><br/>';

                $tqs = "INSERT INTO images (`original_image_name`, `image_file`, `date_created`) VALUES ('" . $_FILES['file']['name'][$i] . "', '" . $new_image_name  . "', now())";
                $tqr = mysqli_query($dbc, $tqs);

                // Select the ID numbers of the last inserted images and store them inside an array.
                // Use the implode() function on the array to have a string of the ID numbers separated by commas.
                // Store the ID numbers in the "image_file_id" column of the "thread" table.

                $tqs = "SELECT `id` FROM `images` WHERE `image_file` IN ('$new_image_name')";
                $tqr = mysqli_query($dbc, $tqs) or die(mysqli_error($dbc));

                $fetch_array = array();
                $row = mysqli_fetch_array($tqr);
                $fetch_array[] = $row['id'];


                /*
                 * This prints e.g.:
                    Array ( [0] => 542 )

                    Array ( [0] => 543 )

                    Array ( [0] => 544 )
                 */
                print_r($fetch_array);

                // Goes over to create the thumbnail images.
                $src = $target_path;
                $dest = $_SERVER['DOCUMENT_ROOT'] . "/gallerysite/multiple_image_upload/thumbs/" . $new_image_name;

                make_thumb($src, $dest, $desired_width);


            } else {//if file was not moved.
                echo $j. ').<span id="error">please try again!.</span><br/><br/>';
            }
        } else {//if file size and file type was incorrect.
            echo $j. ').<span id="error">***Invalid file Size or Type***</span><br/><br/>';
        }
    }
}

                    Array ( [0] => 542 )

                    Array ( [0] => 543 )

                    Array ( [0] => 544 )

542, 543, 544