to mark the end of loop
t = clock ( ) - t ; cout << " Sum ▁ is : ▁ " << sum << endl ; cout << " Time ▁ taken ▁ by ▁ unrolling : ▁ " " ( float ) t ▁ / ▁ CLOCKS _ PER _ SEC ▁ < < ▁ " seconds " return 0 ; }