[RESOLVED] Login from text file?

[Farrow]

Hi all,
I'm making a virtual OS, but I need some help with the login code.
This is what I have so far:

Public Class Login
    Private Sub PictureBox1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox1.Click
        Label1.Visible = False
        Dim Test1 As String = UsernameTextBox.Text
        Dim Test2 As String = TextBox1.Text
        If AllUsers.Contains(Test1) Then
            If AllPasswords.Contains(Test2) Then
                'ADD LOGIN
                MsgBox("works")
            End If
        Else
            Label1.Visible = True
        End If
    End Sub

    Private Sub Login_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim file As New System.IO.StreamReader("Users.txt")
        Dim Length As Integer = file.ReadLine()
        Dim Users(Length) As String
        For i = 0 To Length - 1
            Users(i) = file.ReadLine()
        Next
        AllUsers = Users.ToString()
        file.Close()
        Dim file1 As New System.IO.StreamReader("x86VarServerX10.txt")
        Dim L2 As Integer = file1.ReadLine()
        Dim Passwords(L2) As String
        For i = 0 To L2 - 1
            Passwords(i) = file1.ReadLine()
        Next
        MsgBox(Passwords)
        MsgBox(Users)
    End Sub
End Class

My problem(s) are that the arrays are getting an extra value ;eg length = 3 instead of 2 (which is specified in the text files), so I end up with a 3rd value "Nothing". This is bad because someone could login without a user/password.

My other problem is that the arrays error in the msgbox. Using ToString() results in "System.String[]". How can I fix this?

[cicatrix]

This is probably a good way to learn, although 'virtual OS' is a bit grand title for what you are trying to do
Your first problem seems to be in the fact that you didn't turn Option Strict on. Do that right now and don't ever turn it off.

Dim Length As Integer = file.ReadLine()

the ReadLine method returns a System.String while you try to assign a string value to an Integer variable without even checking what's been in that string.

Secondly, the last call to the ReadLine will most probably return an empty string (a common thing with text files is that the last line is empty) so you should check for that.

Also, if you need to get contents of the file in the string array you can use IO.File.ReadAllLines() method which will return you a string array.

Third. You don't seem to be checking for the existance of the text files you try to open. This may cause an run-time error if something happens with these files or they will be locked by some other problem.
All I/O operations should be enclosed in Try....Catch...End Try block and handle possible exceptions like 'File not found', 'Access denied', etc.

Four. Storing user names and passwords separately is a good way to mess the things up. Storing the passwords in an unencrypted form is the same as not to have password protection at all. Usernames/passwords must be kept in one place and always be encrypted.

Five. Consider using a database instead of text files.

[Farrow]

Thanks for all the info. Right now, though, I'm not really going deep with this. It's just a test, when I get everything down I will start using encryption methods. As for databases, I am extremely new at it, and I would really be glad if you pointed me to a beginner project to learn.

Now, for the string to integer problem - should I use CInt() on it before assigning it?

Lastly - for the Try statement - they're not there because I know they will be. Again, when I finish the whole thing, that's when I'll go into more detail on the whole security and debugging aspects.

[Farrow]

This is my code so far:

Option Strict On
Public Class Login
    Private Sub PictureBox1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox1.Click
        Dim user As String = UsernameTextBox.Text.ToLower()
        Dim pass As String = TextBox1.Text.ToLower()
        If CBool(Array.BinarySearch(AllUsers, user)) = False Then
            MsgBox("works")
        End If
    End Sub
 
    Private Sub Login_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim users As Array = IO.File.ReadAllLines("Users.txt")
        AllUsers = users
        Dim passes As Array = IO.File.ReadAllLines("x86VarServerX10.txt")
        AllPasswords = passes
    End Sub
End Class

My problem now is that the username only works for the first user; In my text file I state two users:
Guest
Admin

When I try to login as Guest, I get the messagebox, with Admin, I don't get anything. What am I doing wrong?

[cicatrix]

The problem is with the way you perform the search.
Read the documentation carefully:

Return Value

Type: System.Int32
The index of the specified value in the specified array, if value is found. If value is not found and value is less than one or more elements in array, a negative number which is the bitwise complement of the index of the first element that is larger than value. If value is not found and value is greater than any of the elements in array, a negative number which is the bitwise complement of (the index of the last element plus 1).

Then you convert the return value to the Boolean one with CBool. Fine thing with CBool function and boolean values in general is that it considers zero to be a false value while all others as true.
The binary search returns zero as the index of the found element, the element is found - fine, but when you convert CBool(0) = False.

Instead just check if a return value is greater than or equal to zero.

P.S.
An Array.IndexOf() method perhaps fits here better than BinarySearch and the readability of the code will he better.

P.P.S.
If you still want to store user names and passes separately you could at least check if

AllUsers.Length = AllPasswords.Length

P.P.P.S
Also, ALWAYS catch possible exceptions when you do file i/o. Disk errors, missing files, access problems and other thing may crush the program at unexpected time.

[Farrow]

Option Strict On
Public Class Login
    Private Sub PictureBox1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox1.Click
        Dim user As String = UsernameTextBox.Text.ToLower()
        Dim pass As String = TextBox1.Text.ToLower()
        If CBool(Array.IndexOf(AllUsers, user)) Then
            MsgBox("works")
        End If
    End Sub
 
    Private Sub Login_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim users As Array = IO.File.ReadAllLines("Users.txt")
        AllUsers = users
        Dim passes As Array = IO.File.ReadAllLines("x86VarServerX10.txt")
        AllPasswords = passes
    End Sub
End Class

Thank you for all the help so far. But I am still not understanding what I should do. If you could please give me an example of something that works, I would be very greatful.

[Farrow]

I am still clueless.

[keystone_paul]

Presumably you've defined AllUsers and AllPasses as global variables as they aren't declared in your class (I hope you have Option Explicit on otherwise as per cicatrix's advice with Option Strict turn it on now and leave it on).

What are you expecting this code to do?

If CBool(Array.IndexOf(AllUsers, user)) Then
    MsgBox("works")
End If

You need to read what cicatrix posted above - IndexOf is a slightly more complicated function than you think. It doesn't readily convert into true/false. Try this code for example :

        Dim AllUsers() As String = {"Guest", "Admin"}

        If CBool(Array.IndexOf(AllUsers, "Guest")) Then MsgBox("Guest works")
        If CBool(Array.IndexOf(AllUsers, "Admin")) Then MsgBox("Admin works")
        If CBool(Array.IndexOf(AllUsers, "Blah")) Then MsgBox("Blah works")

Guest doesn't "work" because the index of "Guest" in the array is zero which CBool converts to false.
Admin "works" because the index of "Admin" in the array is one which is nonzero and so CBool converts to true.
Blah "works" because "Blah" doesn't exist in the array and IndexOf returns -1 which CBool converts to true.

Cicatrix gave you the solution to this problem above.

"Instead just check if a return value is greater than or equal to zero."

    Option Strict On
    Public Class Login
        Private Sub PictureBox1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox1.Click
            Dim user As String = UsernameTextBox.Text.ToLower()
            Dim pass As String = TextBox1.Text.ToLower()
            If Array.IndexOf(AllUsers, user) >= 0 Then
                MsgBox("works")
            End If
        End Sub
     
        Private Sub Login_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
            Dim users As Array = IO.File.ReadAllLines("Users.txt")
            AllUsers = users
            Dim passes As Array = IO.File.ReadAllLines("x86VarServerX10.txt")
            AllPasswords = passes
        End Sub
    End Class

[Farrow]

Oh, ok. Thank you all very much.