Fibonacci in batch

Here a simple programm showing some of the power of batch, just so you get an impression why I think it is a good start to learn how to program:
Fibonacci.bat

1 :: This script prints out all Fibonacci-numbers up

2 :: to a position defined by the user

3 :: Version 1.0

4 :: Date: 2012/01/26

5 :: Author: Lukas Boehm

6 @echo off

7

8 :: Section that asks the user to enter a VALID

9 :: position in the fibonacci-sequence

10 setlocal

11 :input

12 set /p POS=Bitte geben Sie die gewuenschte Stelle in der Folge ein

13 set /a NUM=%POS% + 0

14 echo.

15 if %NUM% neq %POS% (

16 echo Fehler: keine gueltige Zahl!

17 goto input

18 )

19 endlocal & set POS=%POS%

20

21 :: Section that calculates and prints out

22 :: the fibonacci numbers

23 setlocal EnableDelayedExpansion

24 set LAST=0

25 set CURRENT=1

26

27 FOR /L %%N IN (1, 1, %POS%) DO (

28 set SWAP=!CURRENT!

29 set /A CURRENT +=!LAST!

30 echo !LAST!

31 set LAST=!SWAP!

32 )

33 endlocal

34

35 :EOF

36 PAUSE