How to find out which nested for loop is better?

Question

Somebody asked me a question: Which one is the fastest among the below two scenario:

Case 1: assume int count = 0;

for (int i = 0; i < 10; i++)
{
           


        

Answer 1

If you really want to know, make your outer loop a function with a single parameter of the maximum loop count (5 or 10), your inner loop a function which takes a single parameter of the maximum inner loop count (10 or 5), then compile without any optimisation, run both a million times, and time them.

With any optimisation at all, your compiler will inline the functions, and expand the loops, and calculate count as part of the optimisation process. My guess is that they'll do exactly the same amount of work, and you'll see exactly the same times.