std::common_type(std::chrono::duration)

 

C++

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Technical Specifications

 

Utilities library

Type support (basic types, RTTI, type traits)

Dynamic memory management

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initializer_list (C++11)

bitset

hash (C++11)

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rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=

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pair

tuple (C++11)

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piecewise_construct (C++11)

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swap

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Type operations

declval (C++11)

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Date and time utilities

time_point (C++11)

duration (C++11)

system_clock (C++11)

steady_clock (C++11)

high_resolution_clock (C++11)

C-style date and time

 

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 floor (C++17) ceil (C++17) round (C++17) abs (C++17) operator""h (C++14) operator""min (C++14) operator""s (C++14) operator""ms (C++14) operator""us (C++14) operator""ns (C++14)
Helper classes
treat_as_floating_point
duration_values

 

template <class Rep1, class Period1, class Rep2, class Period2> struct common_type<std::chrono::duration<Rep1, Period1>,                    std::chrono::duration<Rep2, Period2>> {     typedef std::chrono::duration<         typename std::common_type<Rep1, Rep2>::type, /*see note*/> type; };		(since C++11)

Exposes the type named type, which is the common type of two std::chrono::durations.

Note

The period of the resulting duration is the greatest common divisor of Period1 and Period2.

std::common_type<> is specialized for std::chrono::duration.

Example

Run this code

#include <iostream>
#include <chrono>
 
// std::chrono already finds the greatest common divisor,
// likely using std::common_type<>. We make the type
// deduction externally. 
 
template <typename T,typename S>
auto durationDiff(const T& t, const S& s)  -> typename std::common_type<T,S>::type
{
    typedef typename std::common_type<T,S>::type Common;
    return Common(t) - Common(s);
}
 
 
int main() 
{
    typedef std::chrono::milliseconds milliseconds;
    typedef std::chrono::microseconds microseconds;
 
    auto ms = milliseconds(30);
    auto us = microseconds(1100);
 
    std::cout << ms.count() << "ms - " << us.count() << "us = " 
              << durationDiff(ms,us).count() <<  "\n";
}

Output:

30ms - 1100us = 28900

See also

common_type (C++11)

deduces the result type of a mixed-mode arithmetic expression (class template)