How to rename uploaded file before saving it into a directory?

Below is the code I used in order to upload files into a directory. It works fine. My main question is:

move_uploaded_file() is the one that saves the uploaded file into the directory, and it is also my guess that move_uploaded_file() is the one that sets the name for it.

How could I change the name of my file to a random number?

I have tried to do so below:

$allowedExts = array("gif", "jpeg", "jpg", "png");
$temp = explode(".", $_FILES["file"]["name"]);
$extension = end($temp);
if ((($_FILES["file"]["type"] == "image/gif") || ($_FILES["file"]["type"] == "image/jpeg") || ($_FILES["file"]["type"] == "image/jpg") || ($_FILES["file"]["type"] == "image/pjpeg") || ($_FILES["file"]["type"] == "image/x-png") || ($_FILES["file"]["type"] == "image/png")) && ($_FILES["file"]["size"] < 100000) && in_array($extension, $allowedExts)) {
    if ($_FILES["file"]["error"] > 0) {
        echo "Return Code: " . $_FILES["file"]["error"] . "<br>";
    } else {

        $fileName = $temp[0] . "." . $temp[1];
        $temp[0] = rand(0, 3000); //Set to random number
        $fileName;

        if (file_exists("../img/imageDirectory/" . $_FILES["file"]["name"])) {
            echo $_FILES["file"]["name"] . " already exists. ";
        } else {
            move_uploaded_file($_FILES["file"]["tmp_name"], "../img/imageDirectory/" . $_FILES["file"]["name"]);
            echo "Stored in: " . "../img/imageDirectory/" . $_FILES["file"]["name"];
        }
    }
} else {
    echo "Invalid file";
}

I tried changing variables such as the $_FILES[“file”][“name”] and replacing it with the $fileName; variable so that the new name can be stored.

Answer

You can simply change the name of the file by changing the name of the file in the second parameter of move_uploaded_file.

Instead of

move_uploaded_file($_FILES["file"]["tmp_name"], "../img/imageDirectory/" . $_FILES["file"]["name"]);

Use

$temp = explode(".", $_FILES["file"]["name"]);
$newfilename = round(microtime(true)) . '.' . end($temp);
move_uploaded_file($_FILES["file"]["tmp_name"], "../img/imageDirectory/" . $newfilename);

Changed to reflect your question, will product a random number based on the current time and append the extension from the originally uploaded file.