| 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) | |
| operator=
| 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";
std::cout << std::chrono::duration_cast<shakes>(sec).count()
<< " shakes\n";
std::cout << std::chrono::duration_cast<jiffies>(sec).count()
<< " jiffies\n";
std::cout << microfortnights(sec).count() << " microfortnights\n";
std::cout << nanocenturies(sec).count() << " nanocenturies\n";
}Output:
1 second is: 100000000 shakes 100 jiffies 0.82672 microfortnights 0.316957 nanocenturies
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