C语言学习：计算时间差

 

#include <io_utils.h>
#include <time_utils.h>
#include <time.h>

#define PI 3.1415926

void DoHardWork() {
  double sum = 0;
  for (int i = 0; i < 10000000; ++i) {
    sum += i * i / PI;
  }
  PRINT_DOUBLE(sum);
}

int main() {
  time_t start_time = time(NULL);
  DoHardWork();
  time_t end_time = time(NULL);
  double diff = difftime(start_time, end_time);
  PRINT_DOUBLE(diff);

  long_time_t start_time_ms = TimeInMillisecond();
  DoHardWork();
  long_time_t end_time_ms = TimeInMillisecond();
  PRINT_LLONG(end_time_ms - start_time_ms);

  clock_t start_time_c = clock();
  DoHardWork();
  clock_t end_time_c = clock();
  PRINT_DOUBLE((end_time_c - start_time_c) * 1.0 / CLOCKS_PER_SEC);
  return 0;
}