Question

我读到我可以用std::chrono显示当前的日期，月份和年份，但我该怎么做？

// Example program
#include <iostream>
#include <string>
#include <chrono>

int main()
{
  using namespace std::chrono;
  cout << std::chrono::day;
}

我执行此代码但它不起作用，我总是收到此

 error: 'day' is not a member of 'std::chrono

我做错了什么？

Answer 1

std::put_time就是您所需要的：

#include <chrono>
#include <iostream>
#include <iomanip>
#include <ctime>    

int main()
{
    auto now = std::chrono::system_clock::to_time_t(std::chrono::system_clock::now());
    std::cout << std::put_time(std::localtime(&now), "%Y-%m-%d") << "\n";
}

打印：

2018年5月14日

Answer 2

A different approach based on std:strftime:

#include <iomanip>
#include <ctime>
#include <chrono>
#include <iostream>

int main()
{
    auto now_c = std::chrono::system_clock::to_time_t(std::chrono::system_clock::now());
    std::tm ptm;
    localtime_s(&ptm, &now_c);
    char buffer[80];
    std::strftime(buffer, sizeof(buffer), "%Y-%m-%d %H:%M:%S ", &ptm);
    std::cout << buffer;
}

Result:

2018-05-14 19:33:11

(localtime_s is outside of std namespace and uses a slightly different interface)

用std :: chrono显示日，月和年？

2 个答案: