使用c ++ chrono打印当前系统时间（以纳秒为单位）

本文介绍了使用c ++ chrono打印当前系统时间（以纳秒为单位）的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

如何使用 std :: chrono 库以以下格式打印当前时间？

How can I print the current time in below format using the std::chrono library?

格式为： hour：minute：second：millisecond：microsecond：nanosecond 。

推荐答案

将代码更改为C ++样式：

Changing the code to C++ style:

#include <chrono> #include <ctime> std::chrono::time_point<std::chrono::system_clock> now = std::chrono::system_clock::now(); auto duration = now.time_since_epoch(); typedef std::chrono::duration<int, std::ratio_multiply<std::chrono::hours::period, std::ratio<8> >::type> Days; /* UTC: +8:00 */ Days days = std::chrono::duration_cast<Days>(duration); duration -= days; auto hours = std::chrono::duration_cast<std::chrono::hours>(duration); duration -= hours; auto minutes = std::chrono::duration_cast<std::chrono::minutes>(duration); duration -= minutes; auto seconds = std::chrono::duration_cast<std::chrono::seconds>(duration); duration -= seconds; auto milliseconds = std::chrono::duration_cast<std::chrono::milliseconds>(duration); duration -= milliseconds; auto microseconds = std::chrono::duration_cast<std::chrono::microseconds>(duration); duration -= microseconds; auto nanoseconds = std::chrono::duration_cast<std::chrono::nanoseconds>(duration); std::cout << hours.count() << ":" << minutes.count() << ":" << seconds.count() << ":" << milliseconds.count() << ":" << microseconds.count() << ":" << nanoseconds.count() << std::endl;

结果：

17:56:14:94:451:679

[旧]

一个简单的例子：

#include <sys/time.h> char fmt[64]; char buf[64]; struct timeval tv; struct tm *tm; gettimeofday (&tv, NULL); tm = localtime (&tv.tv_sec); strftime (fmt, sizeof (fmt), "%H:%M:%S:%%06u", tm); snprintf (buf, sizeof (buf), fmt, tv.tv_usec); printf ("%s\n", buf);

结果：

00:01:32:695240