Lære Using Clocks and Time Points | The <chrono> Library

Understanding how to work with clocks and time points is essential when dealing with time in C++. The chrono library provides several types of clocks, each suited for different timing needs. The two most commonly used clocks are std::chrono::system_clock and std::chrono::steady_clock. Each of these clocks has its own characteristics and typical use cases, which you will explore here.

main.cpp


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#include <iostream>
#include <chrono>

int main()
{
    // Get the current time_point from system_clock
    auto now = std::chrono::system_clock::now();
    std::cout << "Current system_clock time_point: " << now.time_since_epoch().count() << std::endl;
}

The std::chrono::system_clock is designed to represent the current time according to the system's wall clock. This means it reflects the real-world date and time as set on your computer. You typically use system_clock when you want to record timestamps, log events, or display the current date and time to users.

main.cpp


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#include <iostream>
#include <chrono>

int main()
{
    // Get the current time_point from steady_clock
    auto now = std::chrono::steady_clock::now();
    std::cout << "Current steady_clock time_point: " << now.time_since_epoch().count() << std::endl;
}

Unlike system_clock, the std::chrono::steady_clock is designed for measuring time intervals. It is guaranteed never to go backwards, even if the system time is adjusted. This makes it ideal for timing operations, benchmarking, or any situation where you need to measure the duration between two points in time without being affected by changes to the system clock.

Note

Use steady_clock for measuring durations, such as benchmarking code or timing events, because it is not affected by changes to the system clock. Use system_clock when you need to get the current date and time, such as for logging or displaying timestamps.

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main.cpp


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#include <iostream>
#include <chrono>

int main()
{
    // Get the current time_point from system_clock
    auto now = std::chrono::system_clock::now();
    std::cout << "Current system_clock time_point: " << now.time_since_epoch().count() << std::endl;
}

main.cpp


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#include <iostream>
#include <chrono>

int main()
{
    // Get the current time_point from steady_clock
    auto now = std::chrono::steady_clock::now();
    std::cout << "Current steady_clock time_point: " << now.time_since_epoch().count() << std::endl;
}

Note

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Seksjon 2. Kapittel 2