chrono

问题 How can i create a timer that after a certain duration, it does something? so far i have been trying to use the % operation. I made a timer at the start of the function and subtracted the current time (now()function) then i % the difference by 5 because i want 5 seconds to pass: (at the start of the program i defined start as high_resolution_clock::now()) duration<double> dur = start-high_resolution_clock::now(); if(dur%5==0) the error ive been getting is: no operator "==" matches these

问题 My Code looks like: // Next 2 lines should be at the same time auto nowMonotonic = std::chrono::steady_clock::now(); auto nowSystem = std::chrono::system_clock::now(); // Do some calc with nowMonotonic and nowSystem This can happen: auto nowMonotonic = std::chrono::steady_clock::now(); // Some other thread/process interrupts this thread for an // unspecific amount of time... auto nowSystem = std::chrono::system_clock::now(); // Do some calc with nowMonotonic and nowSystem I'm working on a

问题 The default constructor of std::chrono::duration is defined as follows: constexpr duration() = default; (For example, see cppreference.com or the libstdc++ source.) However, cppreference.com also says this about constexpr constructors: A constexpr constructor must satisfy the following requirements: ... every base class and every non-static member must be initialized , either in the constructors initialization list or by a member brace-or-equal initializer. In addition, every constructor

问题 The default constructor of std::chrono::duration is defined as follows: constexpr duration() = default; (For example, see cppreference.com or the libstdc++ source.) However, cppreference.com also says this about constexpr constructors: A constexpr constructor must satisfy the following requirements: ... every base class and every non-static member must be initialized , either in the constructors initialization list or by a member brace-or-equal initializer. In addition, every constructor

问题 Using boost::chrono::steady_clock or std::chrono::steady_clock is suppose to guarantee that physical time is always monotonic and is not affected by date time changes in the system. Here is my question, if I have two processes that need to be immune to system date time changes, is it enough to exchange just the time_since_epoch ? In other words, the time interpretation of the two processes to the same time since epoch will be the same? Specifically I need to answer this question for Windows

问题 Is there a standard implementation to print std::duration as a human readable duration? steady_clock::time_point start = steady_clock::now(); doSomeFoo(); steady_clock::time_point end = steady_clock::now(); std::cout << "Operation took " << may_be_std::theMagic(start-end) << std::endl; Which should print something similar to: "Operation took 10d:15h:12m:14:s" or something similar. 回答1: Agreed there is no standard implementation. Here is how you can write one yourself: #include <iostream>

问题 Instead of using std::chrono::system_clock::now(); I would like to set my own specific hours\minutes\seconds. Similar to how one would go about using struct tm to manually construct a date-time. What is the best way of doing this? 回答1: Any clock provided by <chrono> refers to an epoch, which is different from the point in time one your input delta refers to (based on the comments below the question). So you shouldn't try to use std::chrono::time_point instances (the instantiations clocks deal

问题 How to convert C++ chrono time in UTC to string in UTC? Because in my tests when convert chrono time to string it is using different timezone. Example: #include <iostream> #include <string> #include <chrono> #include <sstream> #include <iomanip> #include <cstdint> #include <ctime> std::string getStringFromDateTime(const std::chrono::system_clock::time_point & value) { std::time_t time_now_t = std::chrono::system_clock::to_time_t(value); std::tm now_tm = *std::localtime(&time_now_t); char buf

问题 I have tried to write a lambda that measures the execution time of arbitrary functions. With a lot of help I have managed that for C++14 and functions having a return value, see Measure execution time of arbitrary functions with C++14 lambda. Then I wanted my code to also work with C++11, therefore I have implemented the same idea with template functions. Finally I have realized that this code does not work for functions having no return value. It has been quite simple to generalize the

问题 If you're not familiar with the Gaffer on Games article "Fix your Timestep", you can find it here: https://gafferongames.com/post/fix_your_timestep/ I'm building a game engine, and in an effort to get more comfortable with std::chrono I've been trying to implement a fixed time step using std::chrono for.. a couple of days now and I can't seem to wrap my head around it. Here is the pseudo-code I'm working towards: double t = 0.0; double dt = 0.01; double currentTime = hires_time_in_seconds();