General Procedures Chapter 4

Different Procedures 4.1 Sub Procedures, Part I 4.2 Sub Procedures, Part II 4.3 Function Procedures 4.4 Modular Design (not on test)

Sub Procedures Part 1 Sub Procedure - part of a program that performs one or more related tasks, has its own name, is written as a separate part of the program. Private Sub ProcedureName() statements End Sub

Example 1 pg.143 Private Sub cmdAdd_Click() Dim num1 as single, num2 as single picResult.cls Call ExplainPurpose picResult.Print num1 = 2 num2 = 3 picResult.Print “The sum of”; num1; “and”; num2; “is”; num1 + num2 End Sub Private Sub ExplainPurpose() picResult.Print “This program displays a sentence” picResult.Print “Identifying two numbers and their sum.” End Sub

Example 2, pg.144 Private Sub cmdAdd_Click() Dim num1 as single, num2 as single picResult.cls Call ExplainPurpose picResult.Print Call Add(2,3) End Sub Private Sub Add(num1 as Single, num2 as Single) picResult.Print “the sum of”; num1; “and”; num2; “is”; num1 + num2 End Sub Private Sub ExplainPurpose() picResult.Print “This program displays a sentence” picResult.Print “Identifying two numbers and their sum.” End Sub

Sub Procedures Part II Passing Values Back from Sub Procedures passed by reference passed by value - use this method when you want to ensure the variable will retain its original value when the Sub terminates  In the Call statement, enclose the variable with an extra parentheses…..Call Triple((amt))  Use ByVal statement…. Private Sub Triple(By Val num as single) NOTE: Look at Practice Problem 3 on page 170

Function Procedures Built-in Visual Basic Function Format, Val, Int, Chr, Len, Mid, InStr (pg 178) User-defined functions Functions that you create and declare Private Function FunctionName (var1 as Type1,…..) as dataType statements FunctionName = expression End Function

Function Example 1, pg 179 Private Sub cmdConvert_Click() picTempC.cls picTemC.Print FtoC(val(txtTempF.Text)) End Sub Private Function FtoC(t as Single) as Single FtoC = (5 / 9) * (t - 32) End Function NOTE: Look at Practice Problem 2 on page 185