I am trying to assign a unique file name to an uploaded file keeping the extension

[devilInDisguise]

I am new to PHP and I am trying to get this code to rename a file and save it in the subdirectory. But I need it to keep the extension. Please Help me!

<?php
$allowedExts = array("txt", "dxf","DXF", "pdf", "png");
$temp = explode(".", $_FILES["file"]["name"]);
$extension = end($temp);

if ((($_FILES["file"]["type"] == "text/plain")
|| ($_FILES["file"]["type"] == "application/octet-stream")
|| ($_FILES["file"]["type"] == "application/pdf")
|| ($_FILES["file"]["type"] == "image/png"))
&& ($_FILES["file"]["size"] < 2000000)
&& in_array($extension, $allowedExts))
{
if ($_FILES["file"]["error"] > 0)
{
echo "Return Code: " . $_FILES["file"]["error"] . "<br>";
}
else
{
echo ".tmpFiles: " . $_FILES["file"]["name"] . "<br>";
echo "Type: " . $_FILES["file"]["type"] . "<br>";
echo "Size: " . ($_FILES["file"]["size"] / 1024) . " kB<br>";
echo "Temp file: " . $_FILES["file"]["tmp_name"] . "<br>";

if (file_exists(".tmpFiles/" . $_FILES["file"]["name"]))
{

echo $_FILES["file"]["name"] . " already exists. ";
}
else
{

move_uploaded_file($_FILES["file"]["tmp_name"],
".tmpFiles/" . $_FILES["file"]["name"]);
echo "Stored in: " . ".tmpFiles/" . $_FILES["file"]["name"];
}
}
}
else
{
echo "Invalid file";
}

include('list.php');

?>
Thanks in advance for you help

[johny10151981]

Describe the error please.

[devilInDisguise]

I am not getting an error I just do not know how to do it. I have tried uniqid() but I am not sure where to put it and what syntax to use