Write a program to upload a file in PHP?

The program to upload a file in PHP is as follows:

<?php

$target_dir = "uploads/";

$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);

$uploadOk = 1;

$imageFileType = strtolower(pathinfo($target_file,PATHINFO_EXTENSION));

if(isset($_POST["submit"])) {

  $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);

  if($check !== false) {

    echo "File is an image - " . $check["mime"] . ".";

    $uploadOk = 1;

  } else {

    echo "File is not an image.";

    $uploadOk = 0;

  }

}

?>