std::chrono::duration_cast

 

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std::chrono::duration

Member functions
duration::duration
duration::operator=
duration::count
duration::zero
duration::min
duration::max
duration::operator+duration::operator-
duration::operator++duration::operator--
duration::operator+=duration::operator-=duration::operator*=duration::operator/=duration::operator%=
Non-member functions
operator+operator-operator*operator/operator% operator==operator!=operator<operator<=operator>operator>=	common_type duration_cast operator""h (C++14) operator""min (C++14) operator""s (C++14) operator""ms (C++14) operator""us (C++14) operator""ns (C++14)
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treat_as_floating_point
duration_values

 

template <class ToDuration, class Rep, class Period> constexpr ToDuration duration_cast(const duration<Rep,Period>& d);		(since C++11)

Converts a std::chrono::duration to a duration of different type ToDuration.

No implicit conversions are used. Multiplications and divisions are avoided where possible, if it is known at compile time that one or more parameters are 1. Computations are done in the widest type available and converted, as if by static_cast, to the result type only when finished.

Parameters

d

-

duration to convert

Return value

d converted to a duration of type ToDuration.

Notes

The function does not participate in the overload resolution unless ToDuration is an instance of std::chrono::duration.

Casting between floating-point durations or between integer durations where the source period is exactly divisible by the target period (e.g. hours to minutes) can be performed implicitly, no duration_cast is needed.

Casting from a floating-point duration to an integer duration is subject to undefined behavior when the floating-point value is NaN, infinity, or too large to be representable by the target's integer type.

Example

This example measures the execution time of a function

Run this code

#include <iostream>
#include <chrono>
#include <thread>
 
void f()
{
    std::this_thread::sleep_for(std::chrono::seconds(1));
}
 
int main()
{
    auto t1 = std::chrono::high_resolution_clock::now();
    f();
    auto t2 = std::chrono::high_resolution_clock::now();
    std::cout << "f() took "
              << std::chrono::duration_cast<std::chrono::milliseconds>(t2 - t1).count()
              << " milliseconds\n";
}

Output:

f() took 1000 milliseconds