Microsoft Visual Basic 2010 Step by Step eBook

Chapter 10 Creating Modules and Procedures 263

Sub BirthdayGreeting (ByVal Person As String)

Dim Msg As String

If Person <> "" Then

Msg = "Happy birthday " & Person & "!"

Else

Msg = "Name not specified."

End If

MsgBox(Msg, , "Best Wishes")

End Sub

The BirthdayGreeting procedure receives the name to be greeted by using the Person

argument, a string variable received by value during the procedure call. If the value of

Person isn’t empty, or null, the specified name is used to build a message string that will

be displayed with a MsgBox function. If the argument is null, the procedure displays the

message “Name not specified .”

Calling a Sub Procedure

To call a Sub procedure in a program, you specify the name of the procedure, and then list

the arguments required by the Sub procedure. For example, to call the BirthdayGreeting

procedure, you could type the following statement:

BirthdayGreeting("Robert")

In this example, the BirthdayGreeting procedure would insert the name “Robert” into

a message string, and the routine would display the following message box:

The space-saving advantages of a procedure become clear when you call the procedure

many times using a variable, as shown in the example below:

Dim NewName As String

Do

NewName = InputBox("Enter a name for greeting.", "Birthday List")

BirthdayGreeting(NewName)

Loop Until NewName = ""

Here the user can enter as many names for birthday greetings as he or she likes. The next

exercise gives you a chance to practice using a Sub procedure to handle another type of

input in a program.