Visual Basic

Dim scr_time As Date
dim ok as boolean


System.Console.WriteLine("Enter screening date & time [DD/MM/YYYY HH/MM]")
        scr_time = System.Console.ReadLine()

        ValidateDate(scr_time, ok)



Sub ValidateDate(ByVal scr_time As String, ByRef bol_isvalid As Boolean)
        If IsDate(scr_time) Then
            bol_isvalid = True
        Else
            bol_isvalid = False
        End If
    End Sub

now >= scr_date

Dim cnt_adult As Integer

System.Console.WriteLine("How many adult tickets required?")
        cnt_adult = System.Console.ReadLine()

        ValidateNumber(cnt_adult, ok)

        If ok Then
            System.Console.WriteLine()
        Else
            System.Console.WriteLine("Incorrect value. Press any key to try again.")
            System.Console.ReadKey()
            GoTo sale
        End If


Sub ValidateNumber(ByVal text As String, ByRef bol_isvalid As Boolean)
        If IsNumeric(text) Then
            bol_isvalid = True
        Else
            bol_isvalid = False
        End If
    End Sub