C++-C11-chrono-获取当前时间、获取阶段时间

C++-C11-chrono-获取当前时间、获取阶段时间

Linux下使用C++11的chrono库获取时间。

#include <chrono>
#include <thread>
#include <iostream>

int64_t getCurrentLocalTimeStamp(){
    std::chrono::time_point<std::chrono::system_clock, 
        std::chrono::milliseconds> tp = std::chrono::time_point_cast<std::chrono::milliseconds>(std::chrono::system_clock::now());
    auto tmp = std::chrono::duration_cast<std::chrono::milliseconds>(tp.time_since_epoch());
    return tmp.count();
    return std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now().time_since_epoch()).count();
}

char* print_time_point(std::chrono::system_clock::time_point timePoint) {
  std::time_t timeStamp = std::chrono::system_clock::to_time_t(timePoint);
  return std::ctime(&timeStamp);
}

int64_t getTimeSpan(){
    auto start = std::chrono::high_resolution_clock::now();
    std::this_thread::sleep_for(std::chrono::milliseconds(1000));
    /*
    std::chrono::nanoseconds
    std::chrono::microseconds
    std::chrono::milliseconds
    std::chrono::seconds
    std::chrono::minutes
    std::chrono::hours
    template< class Clock, class Duration >
    void sleep_until( const std::chrono::time_point<Clock,Duration>& sleep_time )
    */
    auto end = std::chrono::high_resolution_clock::now();
    std::chrono::duration<double, std::milli> elapsed = end - start;
    return elapsed.count();
}

int main(){
    std::cout<<getTimeSpan()<<std::endl;
    std::cout<<getCurrentLocalTimeStamp()<<std::endl;
    std::cout<<print_time_point(std::chrono::high_resolution_clock::now())<<std::endl;
    return 0;
}

输出结果如下：

1000
1681140472905
Mon Apr 10 23:27:52 2023

double类型时间转换std::chrono::duration

近期封装的class Event中WaitFor()的参数需要const std::chrono::duration<_Rep, _Period> &duration，而传入的是double的值，所以做了以下转换。

double dStart;
double dEnd;
double dSpan = dEnd-dStart;
std::chrono::milliseconds ms{(int64_t)dSpan};
或
std::chrono::duration<double, std::milli> elpased = ms;
或
std::chrono::duration<double, std::milli> t(dSpan);