writing function for permutation

[dave]

Hi There
Can anyone help to write permutation function for following formula..
nPr = n!/(n-r)!
where n is length of given string and r is lengh of subset..
for example..if given string is "abcd" and r = 2 then out put shuld be
ab
ac
ad
ba
bc
bd..and so on...

and if r = 3 then output shuld be
abc
abd
acb
acd and so on...

Any help would be highly appreciated..
thnx
dave

 

[CMM]

Do a search on Google for: vb permutations
Lots of interesting algorithms out there.