NAME¶

std::chrono::treat_as_floating_point - std::chrono::treat_as_floating_point

Synopsis¶

Defined in header <chrono>
template <class Rep> (since C++11)
struct treat_as_floating_point : std::is_floating_point<Rep> {};

The std::chrono::treat_as_floating_point trait helps determine if a duration can be
converted to another duration with a different tick period.

Implicit conversions between two durations normally depends on the tick period of
the durations. However, implicit conversions can happen regardless of tick period if
std::chrono::treat_as_floating_point<Rep>::value == true.

Helper variable template

template< class Rep >
inline constexpr bool treat_as_floating_point_v = (since C++17)
treat_as_floating_point<Rep>::value;

Specializations¶

std::chrono::treat_as_floating_point may be specialized for program-defined types.

Example¶

// Run this code

#include <iostream>
#include <chrono>
#include <thread>

void timed_piece_of_code()
{
std::chrono::milliseconds simulated_work(2);
std::this_thread::sleep_for(simulated_work);
}

int main()
{
auto start = std::chrono::high_resolution_clock::now();

std::cout << "Running some timed piece of code..." << '\n';
timed_piece_of_code();

auto stop = std::chrono::high_resolution_clock::now();

// A floating point milliseconds type
using FpMilliseconds =
std::chrono::duration<float, std::chrono::milliseconds::period>;

static_assert(std::chrono::treat_as_floating_point<FpMilliseconds::rep>::value,
"Rep required to be floating point");

// Note that implicit conversion is not allowed here
auto i_ms = std::chrono::duration_cast<std::chrono::milliseconds>(stop - start);

// Note that implicit conversion is allowed here
auto f_ms = FpMilliseconds(stop - start);

std::cout << "Timing stats: " << '\n';

std::cout << " Time in milliseconds, using default rep: "
<< i_ms.count() << '\n';

std::cout << " Time in milliseconds, using floating point rep: "
<< f_ms.count() << '\n';

}

Possible output:¶

Running some timed piece of code...
Timing stats:
Time in milliseconds, using default rep: 2
Time in milliseconds, using floating point rep: 2.57307

See also¶