OT: algorithm for generating all possible combinations with replacement

Dear all,

I have n objects and I want to select k of these with replacement. Do you know
of code which would generate all the possible arrangements? Note that this is
different from the selection of k of n objects without replacement and wanting
to generate all the possible permutations.

Any suggestions? Existing C code would be fantastic btw, but I would be happy
with an algorithm.

Best wishes!