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

Procedures and Functions 36
Recursion
A recursive procedure or function is one that has the ability to call itself until it detects that
some base condition has been satisfied. When the function is called with the base condition,
a result is returned.
The following example uses a recursive function to calculate the factorial of the numbers
42, -42, and 3.14:
Sub Main
Msgbox CalculateFactorial( 42 ) ' Displays 1,40500611775288E+51
Msgbox CalculateFactorial( -42 ) ' Displays "Invalid number for
factorial!"
Msgbox CalculateFactorial( 3.14 ) ' Displays "Invalid number for
factorial!"
End Sub
Function CalculateFactorial( Number )
If Number < 0 Or Number Int( Number ) Then
CalculateFactorial = "Invalid number for factorial!"
ElseIf Number = 0 Then
CalculateFactorial = 1
Else
' This is the recursive call:
CalculateFactorial = Number * CalculateFactorial( Number - 1 )
Endif
End Function
The example returns the factorial of the number 42 by recursively calling the
CalculateFactorial function until it reaches the base condition of 0! = 1.
The recursion levels are set at different levels based on the software platform. For Windows the
recursion level is 5800. For Solaris and Linux, an evaluation of the stacksize is performed and the
recursion level is calculated.
External links
[1] http:/ / en. wikipedia. org/ wiki/ Pass_by_reference#Call_by_reference
Source: http:/ / wiki. services. openoffice. org/ w/ index. php? title=Documentation/ BASIC_
Guide/ Procedures_ and_ Functions&oldid=104495
Principal Authors: Fpe, Ccornell, TJFrazier