Computer Programming Concepts and Visual Basic David I. Schneider

Private Sub cmdDetermine_Click()
Dim nom As String
‘Determine a person’s first name
nom = txtFullName.Text
picFirstName.Cls
picFirstName.Print “The first name is “; FirstName(nom)
End Sub
Private Function FirstName(nom As String) As String
Dim firstSpace As Integer
‘Extract the first name from a full name
firstSpace = InStr(nom, “ “)
FirstName = Left(nom, firstSpace - 1)
End Function
[Run, type Thomas Woodrow Wilson into the text box, and then click the command button.]
The input to a user-defined function can consist of one or more values. Two examples of functions
with several parameters follow. One-letter variable names have been used so the mathematical
formulas will look familiar and be readable. Because the names are not descriptive,
the meanings of these variables are carefully stated in comment statements.
Private Function Hypotenuse(a As Single, b As Single) As Single
‘Calculate the hypotenuse of a right triangle
‘having sides of lengths a and b
Hypotenuse = Sqr(a ^ 2 + b ^ 2)
End Function
Private Function FV(p As Single,r As Single,c As Single,n As Single)
As Single Dim i As Single, m As Single
‘Find the future value of a bank savings account
‘p principal, the amount deposited
‘r annual rate of interest
‘c number of times interest is compounded per year
‘n number of years
‘i interest rate per period
‘m total number of times interest is compounded
i = r / c
m = c * n
FV = p * ((1 + i) ^ m)
End Function
EXAMPLE 3
The following program uses the Hypotenuse function.
Function Procedures 89