Passing Parameters to Functions

When you create your own functions, it is often helpful to pass parameters to the function. These parameters can be used either as data that you want the function to act upon or as settings used to control how the function does its work. How you pass parameters to functions is illustrated in the following macros:

Sub Macro1()
    Dim A As Double

    A = 12.3456
    MsgBox A & "     " & Round(A)
End Sub

Function Round(X As Double) As Double
    Round = Int(X + 0.5)
End Function

This simple macro (Macro1) assigns a value (12.3456) to the variable A. It then displays, in a message box, that number and the result of passing the number to the Round function; the output is 12.3456 and 12. Notice that the parameter should be passed to the function within parentheses.

Also notice that the function does not use the same variable name as it was passed. (The variable A is passed to the function when it is invoked; within the function this value is referred to by the variable name X.) This is because VBA reassigns the value of X (what the function needs) so it matches the value of A (what the program is passing to the function).

VBA allows you to specify multiple parameters to be passed to a function. The parameters simply need to be separated by commas in both the declaration of the function and whenever the function is called. The important thing to remember in passing parameters to functions is that your program must pass the same number of parameters as the function expects, and the parameters must be of matching types and in the proper order.

WordTips is your source for cost-effective Microsoft Word training. (Microsoft Word is the most popular word processing software in the world.) This tip (12962) applies to Microsoft Word 2007, 2010, 2013, 2016, 2019, and 2021. You can find a version of this tip for the older menu interface of Word here: Passing Parameters to Functions.