C-计算时间差

使用 clock() 更能体现出程序的性能。一般使用 clokc() 计算程序真实的运行状况

#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_time1 = time(NULL);
    DoHardWork();
    time_t end_time2 = time(NULL);
    double diff= difftime(start_time1, end_time2);
    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;
}