Write a PHP program to upload a file

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST" && isset($_FILES["file"])) {
    $targetDir = "./";
    $targetFile = $targetDir . basename($_FILES["file"]["name"]);
    
    if (move_uploaded_file($_FILES["file"]["tmp_name"], $targetFile)) {
        echo "File uploaded successfully.";
    } else {
        echo "File upload failed.";
    }
}
?>

<!DOCTYPE html>
<html>
<body>
    <form method="post" enctype="multipart/form-data">
        <input type="file" name="file" required>
        <input type="submit" value="Upload">
    </form>
</body>
</html>