std::chrono::clock_cast

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C-style date and time

Defined in header <chrono>
template <class Dest, class Source, class Duration> auto clock_cast(const std::chrono::time_point<Source, Duration>& t);		(since C++20)

Converts the time point t of a clock Source to an equivalent time point of the clock Dest, using std::chrono::system_clock and/or std::chrono::utc_clock as intermediaries if necessary.

• If the expression std::chrono::clock_time_conversion<Dest, Source>{}(t) is well-formed, returns the result of that expression.
• Otherwise, if at least one of the following two expressions are well-formed, then

• If both expression are well-formed, the conversion is ambiguous, and the program is ill-formed.
• Otherwise, exactly one of the two expressions is well-formed; the result of that expression is returned.

1) std::chrono::clock_time_conversion<Dest, std::chrono::system_clock>{}(
std::chrono::clock_time_conversion<std::chrono::system_clock, Source>{}(t))

2) std::chrono::clock_time_conversion<Dest, std::chrono::utc_clock>{}(
std::chrono::clock_time_conversion<std::chrono::utc_clock, Source>{}(t))

• Otherwise, if at least one of the following two expressions are well-formed, then

• If both expression are well-formed, the conversion is ambiguous, and the program is ill-formed.
• Otherwise, exactly one of the two expressions is well-formed; the result of that expression is returned.

1) std::chrono::clock_time_conversion<Dest, std::chrono::utc_clock>{}(

std::chrono::clock_time_conversion<std::chrono::utc_clock, std::chrono::system_clock>{}(

std::chrono::clock_time_conversion<std::chrono::system_clock, Source>{}(t)))

2) std::chrono::clock_time_conversion<Dest, std::chrono::system_clock>{}(

std::chrono::clock_time_conversion<std::chrono::system_clock, std::chrono::utc_clock>{}(

std::chrono::clock_time_conversion<std::chrono::utc_clock, Source>{}(t)))

• Otherwise, this function does not participate in overload resolution.

Return value

The result of the conversion, determined as described above.

See also

clock_time_conversion (C++20)

traits class defining how to convert time points of one clock to another (class template)