ASP.NET

Dim p1() as Integer = 2467

Protected Sub Page_Load(sender As Object, e As System.EventArgs) Handles Me.Load

        Dim uPassword() As Char = "fortune"
        Dim p1 As Integer = 2
        Dim p1c As Char = "r"
        Dim pMatch As Integer = 1

        Dim input(uPassword.Length - 1) As Char
        For i As Integer = 0 To uPassword.Length - 1
            'Just building the password char array to validate the thought
            input(i) = uPassword(i)

            If (p1 = i) Then
                If (uPassword(i) = p1c) Then
                    pMatch = 0
                End If
            End If
        Next

        Response.Write("<span style=""color: black;"">" & input & "</span>" & _
            "<br /><span style=""color: black;"">" & pMatch.ToString & "</span>")

    End Sub

First on Page_Load the 4 random numbers are generated and store it in one array which 
is public shared , then on login buttom i retreve password based on user name to take one record
and store that passwoard on variable (passdbo) then I do like this

 x1 = (arrNumber(0) - 1)
        a1 = passdbo.Chars(x1)

        x2 = (arrNumber(1) - 1)
        a2 = passdbo.Chars(x2)

        x3 = (arrNumber(2) - 1)
        a3 = passdbo.Chars(x3)

        x4 = (arrNumber(3) - 1)
        a4 = passdbo.Chars(x4)


        passdb = Val(a1 + a2 + a3 + a4)


        pass = Val(TextBox2.Text)

        If String.Compare(passdb, pass) Then
            Response.Redirect("student.aspx")
        Else
            MsgBox("Invalid Username OR Password ")

  End If