[gravypod]

If you are going from 0 -> NUMBER and adding one to a variable every iteration, what will the variable's final result be? NUMBER. The compiler can see this and will just do the following:

    s = i = atoi(argv[1]);

Now the loop is gone.

Edit: This will still happen even if you're doing other stuff in there. GCC will attempt to inline and optimize like this. If it is impossible then you will see a loop with most of the stuff factored out of it.