Bulls and cows: Difference between revisions

</lang>

=={{header|Visual Basic .NET}}==

<lang vbnet>Imports System

Imports System.Text.RegularExpressions

Module Bulls_and_Cows

Function CreateNumber() As String

Dim random As New Random()

Dim sequence As Char() = {"1"c, "2"c, "3"c, "4"c, "5"c, "6"c, "7"c, "8"c, "9"c}

For i As Integer = 0 To sequence.Length - 1

Dim j As Integer = random.Next(sequence.Length)

Dim temp As Char = sequence(i) : sequence(i) = sequence(j) : sequence(j) = temp

Next

Return New String(sequence, 0, 4)

End Function

Function IsFourDigitNumber(ByVal number As String) As Boolean

Return Regex.IsMatch(number, "^[1-9]{4}$")

End Function

Sub Main()

Dim chosenNumber As String = CreateNumber()

Dim attempt As Integer = 0

Console.WriteLine("Number is chosen")

Dim gameOver As Boolean = False

Do

attempt += 1

Console.WriteLine("Attempt #{0}. Enter four digit number: ", attempt)

Dim number As String = Console.ReadLine()

Do While Not IsFourDigitNumber(number)

Console.WriteLine("Invalid number: type four characters. Every character must digit be between '1' and '9'.")

number = Console.ReadLine()

Loop

Dim bulls As Integer = 0

Dim cows As Integer = 0

For i As Integer = 0 To number.Length - 1

Dim j As Integer = chosenNumber.IndexOf(number(i))

If i = j Then

bulls += 1

ElseIf j >= 0 Then

cows += 1

End If

Next

If bulls < chosenNumber.Length Then

Console.WriteLine("The number '{0}' has {1} bulls and {2} cows", _

number, bulls, cows)

Else

gameOver = True

End If

Loop Until gameOver

Console.WriteLine("The number was guessed in {0} attempts. Congratulations!", attempt)

End Sub

End Module