upload-images.php

<?php
declare(strict_types=1);

if (
    !isset($_FILES['files']) &&
    !isset($_FILES['files']['tmp_name']) &&
    !is_iterable($_FILES['files']['tmp_name'])
) {
    echo "No files exist.";
    //Exit execution
}

$file = new stdClass();
$imageExtensions = ["jpeg", "jpg", "png"];
$invalidTypes = implode(', ', $imageExtensions);
$twoMB = 2 * 1024 * 1024;

foreach (array_keys($_FILES['files']['tmp_name']) as $img) {
    $file->name = $_FILES['files']['name'][$img] ?? '';
    $size = $_FILES['files']['size'][$img] ?? 0;
    $file->size = is_numeric($size) ? (int) $size : 0;
    $file->tmpName = $_FILES['files']['tmp_name'][$img] ?? '';
    $file->type = $_FILES['files']['type'][$img] ?? '';
    $fileParts = explode('.', $file->name);
    $file->extension = mb_strtolower(end($fileParts));

    if (!in_array($file->extension, $imageExtensions, true)) {
        //Check For Extension
        echo "{$file->name} is an invalid image type<br/>";
        echo "Please use one of these valid types: {$invalidTypes}<br/>";
        continue;
    }
    if ($file->size > $twoMB) {
        //Error For Large File Size.
        echo "{$file->name} is too large to upload<br/>";
        echo "Please upload a file under two MB<br/>";
        continue;
    }
    //Upload Images to folder named 'gallery'
    move_uploaded_file($file->tmpName, "gallery/{$file->name}");
    echo "Successfully uploaded: {$file->name}<br/>";
    //Do some SQL part here if you want.
}