Question

How to multiply two numbers recursively without using multiplication, division, bitwise and loops in VB.NET

Answer 1

Module Module1

    Sub Main()

        Console.WriteLine("3 * 7 = {0}", multiply(3, 7))
        Console.WriteLine("3 * 0 = {0}", multiply(3, 0))
        Console.WriteLine("0 * 3 = {0}", multiply(0, 3))
        Console.WriteLine("3 * -5 = {0}", multiply(3, -5))
        Console.WriteLine("-3 * 6 = {0}", multiply(-3, 6))

    End Sub

    Function multiply(x As Integer, y As Integer) As Integer

        If (y > 0) Then
            Return (x + multiply(x, y - 1))
        End If

        If (y < 0) Then
            Return -multiply(x, -y)
        End If

        Return 0

    End Function

End Module

' run:
' 
' 3 * 7 = 21
' 3 * 0 = 0
' 0 * 3 = 0
' 3 * -5 = -15
' -3 * 6 = -18

 

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