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std::chrono::duration_cast

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< cpp‎ | chrono‎ | duration

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C++
 
Biblioteca de utilitários
Digite apoio (basic types, RTTI, type traits)
Gerenciamento de memória dinâmica
De tratamento de erros
Utilidades do programa
Variadic funções
Data e hora
Objetos de função
(C++11)
(C++11)
Os operadores relacionais
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Relational operators
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rel_ops::operator!=
rel_ops::operator>
rel_ops::operator<=
rel_ops::operator>=
Pares e tuplas
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Pairs and tuples
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(C++11)
(C++11)
(C++11)
Troque, avançar e avançar
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Swap, forward and move
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(C++11)
(C++11)
(C++11)
(C++11)
 
Utilitários de data e hora
 
std::chrono::duration
Funções de membro
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Member functions
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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%=
Não-membros funções
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Non-member functions
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duration_cast
Classes auxiliares
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Helper classes
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template <class ToDuration, class Rep, class Period>
constexpr ToDuration duration_cast(const duration<Rep,Period>& d);
 (desde C++11)
Converte um std::chrono::duration para uma duração de ToDuration tipo diferente.
Original:
Converts a std::chrono::duration to a duration of different type ToDuration.
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Não conversões implícitas são usados. Multiplicações e divisões são evitados sempre que possível, se ele é conhecido em tempo de compilação que um ou mais parâmetros são 1. Os cálculos são feitos no mais amplo tipo disponível e convertido para o tipo de resultado apenas quando terminado.
Original:
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 to the result type only when finished.
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Índice

[editar] Parâmetros

d -
duração para converter
Original:
duration to convert
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[editar] Valor de retorno

d convertido para uma duração de ToDuration tipo.
Original:
d converted to a duration of type ToDuration.
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[editar] Notas

A função não participar na resolução de sobrecarga, a menos ToDuration é uma instância de std::chrono::duration.
Original:
The function does not participate in the overload resolution unless ToDuration is an instance of std::chrono::duration.
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Fundição de ponto flutuante entre durações ou entre durações inteiros, onde o período de fonte é exatamente divisível por o período de destino (por exemplo, horas para minutos) pode ser realizada implicitamente, não duration_cast é necessário.
Original:
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 implicitamente, no duration_cast is needed.
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[editar] Exemplo

Este exemplo mede o tempo de execução de uma função
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This example measures the execution time of a function
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#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";
}

Saída: 

f() took 1000 milliseconds
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