binary number loop - i.e. going through all binary combinations

All,

A co-worker of mine is working on a program using a financial model that
has some binary tree type logic (sorry - don't know much more about than
that) where she will know how many "levels" she has - say 3 - and then
needs to generate all binary numbers from 000 to 111 - and the process
will do some calculations for each one. She was originally trying a
multistage loop where she set the first digit, then looped through 0 and 1
to set the 2nd, etc. but it was very inefficient plus gets more and more
complicated the greater the number of "levels" the tree will branch too.

My idea was just loop through all the base 10 numbers that are represented
for the number of "levels" being used - say if 3 digit binary you know you
need to go from 0 to 7 (i.e. 0 to (2^n)-1 ) - and then within that one
loop use the binary3. format (or binaryN) on the loop value to get the
binary representation of that number.

Is there any simpler way to do this that we are missing?

Thanks,

Jennifer R. Holdcraft
System Analyst, Market Risk Analytics
American Electric Power
614-583-6761, Audinet 220-6761
Cell: 614-307-4258
jrholdcraft@aep.com