C++ is a very popular programming language that provides a wide range of features to developers. One of those important features is the chrono library which is used for time-related functionality. The chrono library was first introduced in C++11 and has since become a fundamental component for developers who are working on applications that require time precision.
This article aims to demonstrate the use of chrono library in C++
Before moving toward the chrono library use in C++, it’s better to get some knowledge about it.
What is chrono in C++?
chrono is a built-in C++ library that allows users to easily manage date and time. It provides high-precision time and clock support. With chrono, developers can create programs that depend on time, like calendars, reminders, and clocks. The chrono also helps programmers keep track of how much time has passed between different events or actions. It is beneficial for developers who require accurate and reliable time measurements in their applications. It measures the time in seconds, milliseconds, microseconds, and nanoseconds.
How to Use chrono Library in C++?
To use the chrono library, you need to include it in your code by adding the line #include <chrono>. Once this is done, you can access the library’s functionality by using the namespace std::chrono. This namespace will provide you with the necessary tools to perform time-related operations, such as measuring time intervals and scheduling events.
The chrono library can measure time in:
- nanoseconds
- microseconds
- milliseconds
- seconds
- minutes
- hours
- days
- weeks
- months
- years
Utilities of chrono Library in C++
The chrono library defines three main utilities:
1: Clocks
Clocks are an important utility provided by the chrono library in C++. They offer a framework that compares a time-point to actual physical time. The chrono library defines three main clock types: system clock, high resolution clock, and steady clock.
- The system clock represents the global wall clock and is impacted by changes in the system time. Its syntax is “chrono::system_clock”.
- The steady clock, on the other hand, depicts a clock with a monotonic increase that is unaffected by changes in the system time. Its syntax is “chrono::steady_clock“. It is specifically designed to calculate time spans, runs continuously, and time passes equally with each tick of the clock.
- The high resolution clock, as the name suggests, is the clock on the system with the smallest tick period. Its syntax is “chrono::high_resolution_clock“.
All these clocks provide different ways to measure time and can be used according to the needs of the developer.
2: Duration
A duration object uses a count, such as a minute, two hours, or ten milliseconds, to indicate a time period. A duration is the time interval that separates two-time points, with a tick standing in for a single unit of time. This covers time intervals like 20 milliseconds, 20 hours, or 20 seconds. As an illustration, “22 seconds” could be represented as a duration by adding 22 ticks to a 1-second time unit.
3: Time Points
A time_point object is a combination of a duration and a clock, which represents a specific point in time. The epoch is a reference point in time used by a clock and all time_point objects that use the same clock share the same epoch. The time_point object stores the duration and clock type concerning the epoch. The accuracy of the time point depends on the clock being used and can range from arbitrarily coarse to highly precise.
Time points are used to represent specific moments in time, and they can be used to perform calculations such as finding the time difference between two-time points or adding a duration to a time point.
Simple Program to Implement chrono in C++
The following program shows the implementation of chrono in C++:
#include <chrono>
#include <thread>
int main()
{
auto start_time = std::chrono::system_clock::now();
{
std::this_thread::sleep_for(std::chrono::seconds(2));
}
auto end_time = std::chrono::system_clock::now();
std::chrono::duration<double> elapsed_time = end_time - start_time;
std::cout << "Elapsed time: " << elapsed_time.count() << "s";
}
The above program includes three libraries: iostream, chrono, and thread. It creates variables to record the start and end times using the std::chrono::system_clock::now() function, pauses the program for 2 seconds using the std::this_thread::sleep_for function, calculates the elapsed time by subtracting the start and end times, and prints the result in seconds using std::cout and the count() function.
Conclusion
The chrono library is useful for managing date and time in C++ applications. With its ability to provide high-precision time and clock support, it is particularly useful for developers who require accurate time measurement. This article has provided an overview of the syntax and the use of the <chrono> library in C++ with an example. By utilizing the chrono library, developers can ensure that their programs are reliable and efficient and that time-sensitive applications are handled accurately.
