# std::chrono::file_clock::to_sys, std::chrono::file_clock::from_sys

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< cpp‎ | chrono‎ | file clock

template <class Duration> static std::chrono::sys_time</*see below*/> to_sys(const std::chrono::file_time<Duration>& t); | (1) | (since C++20) (optional)
template <class Duration> static std::chrono::file_time</*see below*/> from_sys(const std::chrono::sys_time<Duration>& t); | (2) | (since C++20) (optional)

1) Converts the `file_time` `t` to a `sys_time` representing the same point in time.
2) Converts the `sys_time` `t` to a `file_time` representing the same point in time.

The duration of the return type is computed from `Duration` in an unspecified manner.

These function templates are optional: an implementation may choose to instead provide `to_utc` and `from_utc`.

### Return value

1) A `sys_time` representing the same point in time as the argument.
2) A `file_time` representing the same point in time as the argument.

### Notes

User code should usually use std::chrono::clock_cast, which provides a generic interface to convert time points between clocks, rather than call these functions directly.

### See also

to_utc from_utc [static] (optional) | converts between `file_time` and `utc_time` (public static member function)
clock_cast (C++20) | convert time points of one clock to another (function template)

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