Imports System

Public Module Module1

    Public Sub Main()

        'variables used for every validation below

        dim input as string

        dim num as decimal

        dim valid as boolean

        dim count as integer

        console.writeline("enter anything:")

        'check that something exists

        do

            input = console.readline()

            if input = ""

                console.writeline("invalid")

            end if

        loop until(input <> "")

        console.writeline("enter a number:")

        'check that input is a number

        do

            input = console.readline()

            valid = true

            try

                num = input

            catch

                valid = false

                console.writeline("invalid")

            end try

        loop until(valid = true)

        console.writeline("enter a six character expression:")

        'check that input is 6 characters long

        do

            input = console.ReadLine()

            if input.length <> 6

                console.writeline("invalid")

            end if

        loop until(input.length = 6)

        console.writeline("enter a number between 1 and 31 :")

        'check that input is between 1 and 31

        do

            input = console.readline()

            valid = true

            try

                num = input

                if num < 1 or num > 31

                    valid = false

                    console.writeline("invalid")

                end if

            catch

                valid = false

                console.writeline("invalid")

            end try

        loop until(valid = true)

        console.writeline("enter a word:")

        'check that input is purely comprised of letters

        dim alphabet() as string = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"}

        do

            count = 0

            valid = true

            input = console.readline()

            input = input.ToLower

            for each letter in input

                for i = 0 to alphabet.length-1

                    if letter = alphabet(i)

                        count += 1

                    end if

                next    

            next

            if count <> input.length

                console.writeline("invalid")

                valid = false

            end if

        loop until(valid = true)

​

        console.writeline("enter a date:")

        'check that input is in format DD/MM/YYYY

        dim character as char

        do

            count = 0

            input = console.readline()

            valid = true

            for i = 0 to input.length-1

                character = input.chars(i)

                if i = 2 or i = 5

                    if character.ToString() <> "/"

                        valid = false

                    end if

                else

                    try

                        num = character.ToString()

                    catch

                        valid = false

                    end try

                end if

            next

            if valid = false or input.length <> 10

                console.writeline("invalid")

                valid = false

            end if

        loop until(valid = true)

    End Sub

End Module

​