I'm working with db connection, from what it looks like to me when I finish writing it on sublime there's no error. so, I decided to write localhost/*folder*/*filename*.php in my browser to check the connection and suddenly the browser display; 
Notice: Undefined index: username in C:\xampp\htdocs\Login\login.php on line 4 Notice: Undefined index: pincode in C:\xampp\htdocs\Login\login.php on line 5 {"success":false}
<?php
    $con = mysqli_connect("localhost", "root", "", "test");
    $Username = $_POST["username"];
    $Pincode = $_POST["pincode"];
    $statement = mysqli_prepare($con, "SELECT * FROM users WHERE username = ? AND pincode = ?");
    mysqli_stmt_bind_param($statement, "ss", $Username, $Pincode);
    mysqli_stmt_execute($statement);
    mysqli_stmt_store_result($statement);
    mysqli_stmt_bind_result($statement, $id, $Username, $Pincode);
    $response = array();
    $response["success"] = false;  
    while(mysqli_stmt_fetch($statement)){
        $response["success"] = true;  
        $response["id"] = $id;
        $response["username"] = $Username;
        $response["pincode"] = $Pincode;
    }
    echo json_encode($response);
?>
 
     
     
     
    