Imports System
Imports System.IO
Public Class Form1
    Dim password, username, newpass, newuser As String
    Dim valid As Boolean = False
    Dim fileread As String
    Structure passwordRec
        Dim RecUname As String
        Dim RecPword As String
    End Structure
    Dim SingleRec As passwordRec

    Sub checkvalid()
        'read in password
        password = txtPassword.Text
        'read in username
        username = txtUsername.Text
        'open file
        FileOpen(1, CurDir() & "/user.txt", OpenMode.Input)
        'read from file
        While Not EOF(1)
            Input(1, SingleRec.RecUname)
            Input(1, SingleRec.RecPword)
            'checking credentials against the record
            If username = SingleRec.RecUname And password = SingleRec.RecPword Then
                valid = True
            End If
            If valid Then
                MsgBox("Correct")
                Me.Close()
            Else
                MsgBox("Incorrect")
                Me.Close()
            End If
        End While
        FileClose(1)
    End Sub
    Function register(user, pass) As String
        FileOpen(1, CurDir() & "/user.txt", OpenMode.Append)
        ' user.replace("""", "")
        '   pass.replace("""", "")
        WriteLine(1, user, pass)
        FileClose(1)
    End Function
    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load

    End Sub

    Private Sub btnLogin_Click(sender As System.Object, e As System.EventArgs) Handles btnLogin.Click
        checkvalid()
    End Sub

    Private Sub btnRegister_Click(sender As System.Object, e As System.EventArgs) Handles btnRegister.Click
        newuser = InputBox("Enter username")
        newpass = InputBox("Enter password")
        register(newuser, newpass)
    End Sub
End Class