lecture notes

An intro to subroutines

Sub DisplayName()
Dim FirstName As String = "Josh"
Dim LastName As String = "Waxman"
Dim FullName as String
FullName = FirstName & " " & LastName
MsgBox FullName
End Sub

Private Sub Button1_Click(...) Handles ...
DisplayName
End Sub

Private Sub Button2_Click(...) Handles ...
DisplayName
End Sub


----

Private Sub Button1_Click(...) Handles btnAdd.Click
  'Display the sum of two numbers
  DisplayOpeningMessage
  DisplaySum(2, 3)
End Sub

Sub DisplayOpeningMessage()
  lstResult.Items.Clear()
  lstResult.Items.Add("This program displays a sentence")
  lstResult.Items.Add("identifying two numbers and their sum.")
  lstResult.Items.Add("")
End Sub

Sub DisplaySum(num1 As Double, num2 As Double)
  lstResult.Items.Add("The sum of " & num1 & " and " _
                      & num2 & " is " & num1 + num2 & ".")
End Sub

formal parameters
as opposed to actual parameters
we COPY the actual parameters into the formal parameters


' Get Input

' Processing

' Output Results

top-down design
stepwise refinement
stack
FILO (first in, last out)
push operation (put onto top of stack)
pop operation (taking off top of stack)
call stack
stack frames
use this to understand firstpart, secondpart example