OpenOffice.org BASIC Guide.pdf - OpenOffice.org wiki

Procedures and Functions 34
Passing Parameters
Functions and procedures can receive one or more parameters. Essential parameters must
be enclosed in parentheses after the function or procedure names. The following example
defines a procedure that expects an integer value A and a string B as parameters.
Sub Test (A As Integer, B As String)
' ...
End Sub
Parameters are normally passed by Reference [1] in OpenOffice.org Basic. Changes made
to the variables are retained when the procedure or function is exited:
Sub Test
Dim A As Integer
A = 10
ChangeValue(A)
' The parameter A now has the value 20
End Sub
Sub ChangeValue(TheValue As Integer)
TheValue = 20
End Sub
In this example, the value A that is defined in the Test function is passed as a parameter to
the ChangeValue function. The value is then changed to 20 and passed to TheValue, which
is retained when the function is exited.
You can also pass a parameter as a value if you do not want subsequent changes to the
parameter to affect the value that is originally passed. To specify that a parameter is to be
passed as a value, ensure that the ByVal keyword precedes the variable declaration in the
function header.
In the preceding example, if we replace the ChangeValue function then the superordinate
variable A remains unaffected by this change. After the call for the ChangeValue function,
variable A retains the value 10.
Sub ChangeValue(ByVal TheValue As Integer)
TheValue = 20
End Sub