Difference between std::system_clock and std:: steady_clock ?

In C++, std::system_clock and std::steady_clock are two time point types defined in the <chrono> library for handling time and date. They have several key differences:

1. Clock Types:

   • std::system_clock: This is a system-wide clock that reflects real-world time. It can be adjusted, and therefore is not guaranteed to be monotonic. For example, system time can be adjusted by users or via Network Time Protocol (NTP).

   • std::steady_clock: This is a clock that is always monotonic, regardless of system time changes. It is primarily used for measuring time intervals and ensuring time continuity, making it well-suited for timing and calculating elapsed time.

2. Primary Uses:

   • std::system_clock is typically used for applications that depend on real-world date and time, such as logging, timestamps, and synchronizing with other systems.

   • std::steady_clock is mainly used for applications requiring high time guarantees, such as performance testing, game loops, and event measurement, where the key is to guarantee the relative continuity of time without being affected by system time adjustments.

3. Examples:

   • Suppose you are developing a logging system where recording the exact time of information is crucial for analyzing the sequence and timing of events afterward. In this case, you would choose to use std::system_clock because it provides timestamps consistent with real-world time.

   • Another example is if you are developing a game or timing application that requires precise measurement of time intervals to avoid inaccurate timing due to system time adjustments. In such cases, using std::steady_clock is the better choice as it ensures the continuity and accuracy of timing.

In summary, the choice between std::system_clock and std::steady_clock depends on the specific requirements of the application, whether it needs to synchronize with real-world time, or places greater emphasis on the stability and continuity of time.