W3cubDocs

/C++

std::chrono::duration

Defined in header <chrono> 
template<
    class Rep, 
    class Period = std::ratio<1> 
> class duration;
 (since C++11)

Class template std::chrono::duration represents a time interval.

It consists of a count of ticks of type Rep and a tick period, where the tick period is a compile-time rational constant representing the number of seconds from one tick to the next.

The only data stored in a duration is a tick count of type Rep. If Rep is floating point, then the duration can represent fractions of ticks. Period is included as part of the duration's type, and is only used when converting between different durations.

Member types

Member type Definition
rep Rep, an arithmetic type representing the number of ticks
period Period, a std::ratio representing the tick period (i.e. the number of seconds per tick)

Member functions

 constructs new duration
(public member function)
assigns the contents
(public member function)
returns the count of ticks
(public member function)
[static]
 returns the special duration value zero
(public static member function)
[static]
 returns the special duration value min
(public static member function)
[static]
 returns the special duration value max
(public static member function)
implements unary + and unary -
(public member function)
increments or decrements the tick count
(public member function)
implements compound assignment between two durations
(public member function)

Non-member functions

 specializes the std::common_type trait
(class template specialization)
implements arithmetic operations with durations as arguments
(function template)
compares two durations
(function template)
converts a duration to another, with a different tick interval
(function template)
(C++17)
 converts a duration to another, rounding down
(function template)
(C++17)
 converts a duration to another, rounding up
(function template)
(C++17)
 converts a duration to another, rounding to nearest, ties to even
(function template)
(C++17)
 obtains the absolute value of the duration
(function template)

Helper types

Type Definition
std::chrono::nanoseconds duration</*signed integer type of at least 64 bits*/, std::nano>
std::chrono::microseconds duration</*signed integer type of at least 55 bits*/, std::micro>
std::chrono::milliseconds duration</*signed integer type of at least 45 bits*/, std::milli>
std::chrono::seconds duration</*signed integer type of at least 35 bits*/>
std::chrono::minutes duration</*signed integer type of at least 29 bits*/, std::ratio<60>>
std::chrono::hours duration</*signed integer type of at least 23 bits*/, std::ratio<3600>>

Note: each of the predefined duration types covers a range of at least ±292 years.

Helper classes

 indicates that a duration is convertible to duration with different tick period
(class template)
constructs zero, min, and max values of a tick count of given type
(class template)

Literals

Defined in inline namespace std::literals::chrono_literals
(C++14)
 A std::chrono::duration literal representing hours
(function)
(C++14)
 A std::chrono::duration literal representing minutes
(function)
(C++14)
 A std::chrono::duration literal representing seconds
(function)
(C++14)
 A std::chrono::duration literal representing milliseconds
(function)
(C++14)
 A std::chrono::duration literal representing microseconds
(function)
(C++14)
 A std::chrono::duration literal representing nanoseconds
(function)

Example

This example shows how to define several custom duration types and convert between types:

#include <iostream>
#include <chrono>
 
int main()
{
    using shakes = std::chrono::duration<int, std::ratio<1, 100000000>>;
    using jiffies = std::chrono::duration<int, std::centi>;
    using microfortnights = std::chrono::duration<float, std::ratio<12096,10000>>;
    using nanocenturies = std::chrono::duration<float, std::ratio<3155,1000>>;
 
    std::chrono::seconds sec(1);
 
    std::cout << "1 second is:\n";
 
    // integer scale conversion with no precision loss: no cast
    std::cout << std::chrono::microseconds(sec).count() << " microseconds\n"
              << shakes(sec).count() << " shakes\n"
              << jiffies(sec).count() << " jiffies\n";
 
    // integer scale conversion with precision loss: requires a cast
    std::cout << std::chrono::duration_cast<std::chrono::minutes>(sec).count()
              << " minutes\n";
 
    // floating-point scale conversion: no cast
    std::cout << microfortnights(sec).count() << " microfortnights\n"
              << nanocenturies(sec).count() << " nanocenturies\n";
}

Output:

1 second is:
1000000 microseconds
100000000 shakes
100 jiffies
0 minutes
0.82672 microfortnights
0.316957 nanocenturies

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/cpp/chrono/duration