Agfdhyk

I've JUST started doodling with VB.Net
and I need some advice for a small task I've given myself.

What I want is that the contents of a list can be used as variables.

I've made a "logon" thing" like this:

Sub Main()

    Dim username As String

    Dim password As Integer

    Dim nope As String = "!!!NO ACCESS!!!"

    Dim ukjent As String = "!!!UNKNOWN USER!!!"



    Console.Write("Enter your name: ")

    username = Console.ReadLine()

    Console.Write("Enter Password: ")

    password = Console.ReadLine()



    If username = "jarvis" And password = 1337 Then

        Console.ForegroundColor = ConsoleColor.Green

        Console.WriteLine("Welcome Jarvis")

        Console.WriteLine("Please enter numerical value")



        Dim X As Decimal = Console.ReadLine()

        Dim y As Decimal = Console.ReadLine()

        Dim z As Decimal = Console.ReadLine()

        Dim i As Decimal



        i = X + y + z



        Console.WriteLine(i)

        Console.WriteLine()



    Else

        Console.ForegroundColor = ConsoleColor.Red

        Console.WriteLine(nope)



    End If

    Console.ReadLine()

If I want to use lists where I input more "usernames" and more "passwords" how should I do this?

Could I do it like this?

Dim username() As String ={"User1","User2"}

Dim password() As Integer ={ 123, 321}

How would I recall the values in the lists?
I know for now I'm not considering matching user1 to password 123. but that can come at a later stage, trying to build piece by piece.

You don't want your user to know if it is the username or password or both that is wrong; only that the long-in is not valid. Don't help the hacker.

TryParse takes the string that user types in. Yes, it is a string even if numbers are typed in. Look up Console.ReadLine and you will see it returns a string.

TryParse will test the string to see if it can be converted to an integer. If it succeeds it will place the value into the password variable (in this example) and if it fails a zero will be placed in password.

The .Keys method of the Dictionary returns a collection of all the keys. We check with the Contains method to see if the input username is present. If it is we use the key username to retrieve the value associated with it. If the username is not there we kick the bum out.

Finally we checked the stored password against the entered password.

All this checking is because we can't trust user to enter exactly what we expect them to enter.

Sub Main()

        Dim X, Y, Z As Decimal

        Dim StoredPassword As Integer 'refers to what is in the Dictionary

        Dim username As String = ""

        Dim password As Integer

        Dim nope As String = "!!!NO ACCESS!!!"

        Dim Users As New Dictionary(Of String, Integer) From {{"Mathew", 123}, {"Mark", 456}, {"Luke", 321}}

        Console.Write("Enter your name: ")

        username = Console.ReadLine()

        Console.Write("Enter Password: ")



        Integer.TryParse(Console.ReadLine(), password)

        If Users.Keys.Contains(username) Then

            StoredPassword = Users(username)

        Else

            Console.ForegroundColor = ConsoleColor.Red

            Console.WriteLine(nope)

            Console.ReadLine()

            End

        End If

        If StoredPassword = password Then

            Console.ForegroundColor = ConsoleColor.Green

            Console.WriteLine("Successful Login")

            Console.WriteLine($"Welcome {username}!")

            Console.ForegroundColor = ConsoleColor.White

        Else

            Console.ForegroundColor = ConsoleColor.Red

            Console.WriteLine(nope)

            Console.ReadLine()

            End

        End If



        Console.WriteLine("Please enter numerical value")

        Decimal.TryParse(Console.ReadLine(), X)

        Console.WriteLine("Please enter numerical value")

        Decimal.TryParse(Console.ReadLine(), Y)

        Console.WriteLine("Please enter numerical value")

        Decimal.TryParse(Console.ReadLine(), Z)

        Dim i As Decimal



        i = X + Y + Z



        Console.WriteLine($"The sum is {i}")



        Console.ReadLine() 'keeps the console window open

End Sub