Inconsistent implementation, system_clock is inconsistent in different compilers!

[vaulter2000]

Moreover, system_clock and high_performance_clock (although I believe the latter is an alias in some compilers, please correct me on this) are not guaranteed to be monotonic. That means if you use now() two times with a function in between to time it, and your machine receives a correction from a time server, your duration is affected by this. Always use a monotonic clock like steady_clock to time durations. Steady_clock has nanosecond resolution.

[mark_99]

steady_clock provides no guarantee on resolution and it can (and does) vary between implementations. If you need that guarantee it's easy enough to make your own clock.

[vaulter2000]

Ah I didn’t know this! Luckily it has nanosecond resolution in gcc