#include <sys/time.h>

#include <stdio.h>

#include <ctime>

#include <chrono>

#include <iomanip>

#include <unistd.h> // for "usleep"

#include <iostream>

#include <thread>

#define print(x) std::cout << x << std::endl

typedef std::chrono::high_resolution_clock::time_point chtime;

float timedifference_msec(struct timeval t0, struct timeval t1)

{

return (t1.tv_sec - t0.tv_sec) * 1000.0f + (t1.tv_usec - t0.tv_usec) / 1000.0f;

}

int main()

{

// Method No.1 <-- Do not know why ... it is not accurate !!

clock_t start, end;

float elapsedTime;

// random seed

srand((unsigned)time(0));

start = clock();

// do something...

usleep(4 * 1000 * 1000); // 1s

end = clock();

elapsedTime = (float)(end - start) / CLOCKS_PER_SEC;

print("花费了" << elapsedTime << "秒");

struct timeval t1_sys;

struct timeval t2_sys;

float elapsed;

gettimeofday(&t1_sys, 0);

usleep(1 * 1000 * 1000);

gettimeofday(&t2_sys, 0);

elapsed = timedifference_msec(t1_sys, t2_sys);

printf("Code executed in %f milliseconds.\n", elapsed);

// Method No.2 <-- Use this instead of the 1st method

// ref: https://www.jianshu.com/p/0ccbf45491de

// where "auto" is "std::chrono::time_point"

// auto t1 = std::chrono::system_clock::now();

chtime t1 = std::chrono::high_resolution_clock::now();

// do something...

usleep(0.314 * 1000 * 1000); // 0.314 s

std::this_thread::sleep_for(std::chrono::seconds(1));

// std::chrono::nanoseconds duration<64bits+, std::nano>

// std::chrono::microseconds duration<55bits+, std::micro>

// std::chrono::milliseconds duration<45bits+, std::milli>

// std::chrono::seconds duration<35bits+>

// std::chrono::minutes duration<29bits+, std::ratio<60>>

// std::chrono::hours duration<23bits+, std::ratio<3600>>

// std::chrono::days c++20 duration<25bits+, std::ratio<86400>>

// std::chrono::weeks c++20 duration<22bits+, std::ratio<604800>>

// std::chrono::months c++20 duration<20bits+, std::ratio<2629746>>

// std::chrono::years c++20 duration<17bits+, std::ratio<31556952>>

// auto t2 = std::chrono::system_clock::now();

auto t2 = std::chrono::high_resolution_clock::now();

std::chrono::duration<double> diff = t2 - t1;

print("use " << diff.count() << " s\n");

bool res = diff.count() > 0.0;

print(res);

auto nanos = std::chrono::duration_cast<std::chrono::nanoseconds>(t2 - t1);

print("use " << diff.count() << " s\n");

std::chrono::duration<double, std::nano> fp_nanos = t2 - t1;

print("use " << diff.count() << " s\n");

print("======= get time stamp ======");

auto t = std::time(nullptr);

auto tm = *std::localtime(&t);

print(std::put_time(&tm, "%Y/%m/%d %H:%M:%S"));

return 0;

}