int njbrzdfnzdfond = rand () % 101;
will give you a random number from 0 through 100, and store it in njbrzdfnzdfond.
EDIT: Your original wording is kind of vauge;
int vhasdjklhvasdfjkh = rand () % 100;
will give you a random number from 0 through 99 and store it in vhasdjklhvasdfjkh.