file upload تغییر نام فایل آپلود شده هنگام آپلود

[tehranknai]

سلام من کد زیر رو برای آپلود عکس دارم اما مشکل اینجاست که وقتی یه عکس با همون اسم باشه جایگزین قبلی میشه . میخام هر دفعه که یه عکس آپلودمیشه یه اسم جدید و متفاوت بهش بده که تکراری نباشه . شنیدم که یا گرفتن زمان یا salt میشه این کار رو کرد اما چیزی که متوجه بشم پیدا نکردم .



<?php

if (isset($_POST['submit']) && !empty($_FILES["fileToUpload"]["tmp_name"])) {
$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);






$uploadOk = 1;
$imageFileType = strtolower(pathinfo($target_file, PATHINFO_EXTENSION));
$message = array();
// Check if image file is a actual image or fake image
if (isset($_POST["submit"])) {
$check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
if ($check !== false) {
$message[] = "File is an image - " . $check["mime"] . ".";
$uploadOk = 1;
} else {
$message[] = "File is not an image.";
$uploadOk = 0;
}
}

// Check if file already exists
if (file_exists($target_file)) {
$message[] = "Sorry, file already exists.";
$uploadOk = 0;
}

// Check file size
if ($_FILES["fileToUpload"]["size"] > 500000) {
$message[] = "Sorry, your file is too large.";
$uploadOk = 0;
}

// Allow certain file formats
if ($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"
&& $imageFileType != "gif") {
$message[] = "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
$uploadOk = 0;
}

// Check if $uploadOk is set to 0 by an error
if ($uploadOk == 0) {
$message[] = "Sorry, your file was not uploaded.";

// if everything is ok, try to upload file
} else {
if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
$message[] = "The file " . basename($_FILES["fileToUpload"]["name"]) . " has been uploaded.";
} else {
$message[] = "Sorry, there was an error uploading your file.";
}
}
}
?>

[tehranknai]

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