Functions In VB

[VelMurugan]

Creating Your Own Functions

The general format of a function is as follows:

Public  Function functionName (Arg As dataType,..........) As dataType

or

Private  Function functionName (Arg As dataType,..........) As dataType

* Public indicates that the function is applicable to the whole program and Private indicates that the function is only applicable to a certain module or procedure.

Example :

In this example, a user can calculate future value of a certain amount of money he has today based on the interest rate and the number of years from now supposing  he will invest this amount of money somewhere .The calculation is based on the compound interest rate.

Code Select Expand

Public Function FV(PV As Variant, i As Variant, n As Variant) As Variant
'Formula to calculate Future Value(FV)
'PV denotes Present Value
FV = PV * (1 + i / 100) ^ n
End Function

Code Select Expand

Private Sub compute_Click()
'This procedure will calculate Future Value
Dim FutureVal As Variant
Dim PresentVal As Variant
Dim interest As Variant
Dim period As Variant
PresentVal = PV.Text
interest = rate.Text
period = years.Text

FutureVal = FV(PresentVal, interest, period)
MsgBox ("The Future Value is " & FutureVal)
End Sub
   
Example :

The following program will automatically compute examination grades based on the marks that a student obtained.

Code Select Expand

Public Function grade(mark As Variant) As String
    Select Case mark
    Case Is >= 80
    grade = "A"
    Case Is >= 70
    grade = "B"
    Case Is >= 60
    grade = "C"
    Case Is >= 50
    grade = "D"
    Case Is >= 40
    grade = "E"
    Case Else
    grade = "F"
    End Select
End Function

Private Sub compute_Click()
grading.Caption = grade(mark)