如何获得high_resolution_clock的精度？ [英] How to get the precision of high_resolution_clock?

问题描述

C ++ 11定义 high_resolution_clock ，它具有 period 和 。但我不知道如何获得该时钟的精确。

或者，如果我不能得到精度，我不知何故至少得到一个计数在最小可表示持续时间之间的纳秒？可能使用 period ？

  #include< iostream> 
 #include< chrono> 
 void printPrec（）{
 std :: chrono :: high_resolution_clock :: rep x = 1; 
 //这不是初始化'period'的正确方法：
 // high_resolution_clock :: period y = 1; 
 
 std :: cout<< 最小周期是
< / *在这里用'x'或'y'做什么？ * / 
<< nanos\\\
; 
} 
  

解决方案

code> high_resolution_clock :: period :: num / high_resolution_clock :: period :: den 秒。您可以这样打印：

  std :: cout< （double）std :: chrono :: high_resolution_clock :: period :: num 
 / std :: chrono :: high_resolution_clock :: period :: den; 
  

为什么？时钟的 :: period 成员定义为时钟的节拍周期（以秒为单位）。它是 std :: ratio 的一种特殊化，它是一个在编译时表示比率的模板。它提供了两个积分常数： num 和 den ，分别是分数的分子和分母。

C++11 defines high_resolution_clock and it has the member types period and rep. But I can not figure out how I can get the precision of that clock.

Or, if I may not get to the precision, can I somehow at least get a count in nanoseconds of the minimum representable time duration between ticks? probably using period?

#include <iostream>
#include <chrono>
void printPrec() {
    std::chrono::high_resolution_clock::rep x = 1;
    // this is not the correct way to initialize 'period':
    //high_resolution_clock::period y = 1;

    std::cout << "The smallest period is "
              << /* what to do with 'x' or 'y' here? */
              << " nanos\n";
}

解决方案

The minimum representable duration is high_resolution_clock::period::num / high_resolution_clock::period::den seconds. You can print it like this:

std::cout << (double) std::chrono::high_resolution_clock::period::num
             / std::chrono::high_resolution_clock::period::den;

Why is this? A clock's ::period member is defined as "The tick period of the clock in seconds." It is a specialization of std::ratio which is a template to represent ratios at compile-time. It provides two integral constants: num and den, the numerator and denominator of a fraction, respectively.

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