Exercise
Function calculator, params and return value of Main
Objetive
Write a Visual Basic (VB.Net) program to calculate a sum, subtraction, product or division, analyzing the command line parameters:
calc 5 + 379
(Parameters must be a number, a sign, and another number; allowed signs are + - * x / )
This version must return the following error codes:
1 if the number of parameters is not 3
2 if the second parameter is not an accepted sign
3 if the first or third parameter is not a valid number
0 otherwise
Code
Imports System
Public Class exercise126
Public Shared Function Main(ByVal args As String()) As Integer
If args.Length <> 3 Then
Console.WriteLine("Error!")
Console.WriteLine("Usage: number1 operand number2")
Console.WriteLine("Where operand can be + - / * x ·")
Return 1
End If
Try
Dim number1 As Integer = Convert.ToInt32(args(0))
Dim number2 As Integer = Convert.ToInt32(args(2))
Select Case args(1)
Case "+"
Console.WriteLine(number1 + number2)
Exit Select
Case "-"
Console.WriteLine(number1 - number2)
Exit Select
Case "/"
Console.WriteLine(number1 / number2)
Exit Select
Case "*", "x", "·"
Console.WriteLine(number1 * number2)
Exit Select
Case Else
Console.WriteLine("Error!")
Console.WriteLine("Operand must be + - / * x or ·")
Return 2
Exit Select
End Select
Catch __unusedException1__ As Exception
Console.WriteLine("Error!")
Console.WriteLine("Not a valid number")
Return 3
End Try
Return 0
End Function
End Class