CODEWITHSUNDEEP
vb.netloopsiteration
High Zedd
High Zedd

Reputation: 55

I want to make my program execute till I manually exit it

I have created a console program using vb . Net to calculate an entered number factorial, but it only executes once before I exiting, how can I make the program run until the user wants to exit? Here is the code I used 

Module factorial 

 

    Dim factorial = 1, i, num As Integer

    Sub Main()

        Console.Write("Enter a number to find a factorial of it : ")

        num = Console.ReadLine()

 

        factorial = 1

        For i = 1 To num

            factorial = factorial * i

        Next

 

        Console.WriteLine("Factorial of {0} is {1}", num, factorial)

 

       

 

    End Sub

 

End Module

Upvotes: 0

Views: 90

Answers (2)

Blackwood
Blackwood

Reputation: 4534

To process more than one input from the user, you need to put your code inside a loop. You will need a way for the user to indicate that it's time to finish (for example by typing "Quit" instead of a number.

You should also make sure the string entered by the user is valid before converting it to an Integer. You can do that by using Integer.TryParse.

Finally, you should allow for the possiibility that the factorial is very large. Using a Long instead of an Integer for the factorial will help, but the factorial may still be too large, so you can use Try/Catch to check for an Overflow and send an error message. If you want to handle numbers of any size, you can research BigInteger.

Module factorial
    Sub Main()
        Do
            Console.Write("Enter a number to find its factorial, or Quit to end the program:")
            Dim inString As String = Console.ReadLine
            If inString.ToUpper = "QUIT" Then Exit Sub

            Dim num As Integer
            If Integer.TryParse(inString, num) Then
                Dim factorial As Long = 1
                Try
                    For i As Integer = 2 To num
                        factorial *= i
                    Next
                    Console.WriteLine("Factorial of {0} is {1}", num, factorial)
                Catch ex As OverflowException
                    Console.WriteLine("Factorial of {0} is too large", num)
                End Try
            End If
        Loop
    End Sub
End Module

Upvotes: 1

Vlad DX
Vlad DX

Reputation: 4730

Console.ReadKey() will allow you to make program waiting for pressing any key.

Console.ReadKey Method

If you need your program calculating more and more factorials, you should wrap all the code into infinite loop like that:

Do
    Something
Loop

Upvotes: 1

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