如何在使用C ++创建的测验程序中插入倒数计时器? [英] How to insert a countdown timer in a quiz program that is created using c++?

问题描述

所有带有5分的10个问题都必须在时间内回答.因此，应该显示每个问题n剩余时间所消耗的时间.有人可以帮忙吗?

All the 10 questions with 5 marks need to be answered within time. so the time consumed for each question n remaining time should be displayed. can anybody help?

推荐答案

便携式C ++解决方案是使用 boost.chrono .

A portable C++ solution would be to use chrono::steady_clock to measure time. This is available in C++11 in the header <chrono>, but may well be available to older compilers in TR1 in <tr1/chrono> or boost.chrono.

稳定时钟总是以尽可能均匀"的速率前进，这是在多任务多线程平台上的重要考虑因素.稳定时钟也独立于任何类型的挂钟"，例如系统时钟(可以随时任意操纵).

The steady clock always advances at a rate "as uniform as possible", which is an important consideration on a multi-tasking multi-threaded platform. The steady clock is also independent of any sort of "wall clock", like the system clock (which may be arbitrarily manipulated at any time).

(注意:如果您的实现中没有 steady_clock ，请查找 monotonic_clock .)

(Note: if steady_clock isn't in your implementation, look for monotonic_clock.)

< chrono> 类型使用起来有点麻烦，因此这里有一段示例代码，它返回稳定的时间戳(或者更确切地说，是您喜欢的任何时钟的时间戳，例如 high_resolution_clock ):

The <chrono> types are a bit fiddly to use, so here is a sample piece of code that returns a steady timestamp (or rather, a timestamp from whichever clock you like, e.g. the high_resolution_clock):

template <typename Clock>
long long int clockTick(int multiple = 1000)
{
  typedef typename Clock::period period;
  return (Clock::now().time_since_epoch().count() * period::num * multiple) / period::den;
}

typedef std::chrono::monotonic_clock myclock;  // old
typedef std::chrono::steady_clock yourclock;   // C++11

用法:

long long int timestamp_ms = clockTick<myclock>();         // milliseconds by default
long long int timestamp_s  = clockTick<yourclock>(1);      // seconds
long long int timestamp_us = clockTick<myclock>(1000000);  // microseconds

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