Measure time for executing C program by using Netbeans

Question

I have a problem about Netbeans. This is my code :

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

 int main(){
  int i;
  clock_t start, finish;
  start = clock();
  for(i = 0; i < 10000000000; i++);
  finish = clock();
  printf("%f", (float)(finish-start)/CLOCKS_PER_SEC);
  return 0;
   }

When I run the program on Netbeans 8.1, the output is 0.000000, but it is 0.2100000 when I tried on Dev C.

maybe som different optimization level? Try to put some dummy calculation in the for body. — Felice Pollano, May 21 '16 at 08:43

score 0 · Accepted Answer · answered May 21 '16 at 11:13

It is likely that your for loop is optimized away by the compiler, as the loop has no side effects (i.e. does not affect the rest of the program in any way).

It's not clear what you want to achieve. Do you want to learn how to measure execution time? Then use calls to usleep() or sleep() or while (clock() < XXX); between the measurements to delay the system for some time. Or do you want to learn the execution time of specific algorithm? Then put that algorithm in the code instead of the dummy for loop.

Measure time for executing C program by using Netbeans

1 Answers1