Namespace
Varianti

std::chrono::duration_cast

Da cppreference.com.
< cpp‎ | chrono‎ | duration

 
 
Utilità libreria
Tipo di supporto (basic types, RTTI, type traits)
Gestione della memoria dinamica
La gestione degli errori
Programma di utilità
Funzioni variadic
Data e ora
Funzione oggetti
initializer_list(C++11)
bitset
hash(C++11)
Gli operatori relazionali
Original:
Relational operators
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rel_ops::operator!=
rel_ops::operator>
rel_ops::operator<=
rel_ops::operator>=
Coppie e tuple
Original:
Pairs and tuples
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pair
tuple(C++11)
piecewise_construct_t(C++11)
piecewise_construct(C++11)
Swap, in avanti e spostare
Original:
Swap, forward and move
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swap
forward(C++11)
move(C++11)
move_if_noexcept(C++11)
declval(C++11)
 
 
std::chrono::duration
Membri funzioni
Original:
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%=
Non membri funzioni
Original:
Non-member functions
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common_type
operator+
operator-
operator*
operator/
operator%
operator==
operator!=
operator<
operator<=
operator>
operator>=
duration_cast
Helper classi
Original:
Helper classes
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treat_as_floating_point
duration_values
 
template <class ToDuration, class Rep, class Period>
constexpr ToDuration duration_cast(const duration<Rep,Period>& d);
(dal C++11)
Converte un std::chrono::duration per una durata di ToDuration tipo diverso.
Original:
Converts a std::chrono::duration to a duration of different type ToDuration.
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Conversioni implicite non sono utilizzati. Moltiplicazioni e divisioni vengono evitate quando possibile, se è noto al momento della compilazione che uno o più parametri sono 1. I calcoli sono fatti nel più ampio tipo disponibile e convertito nel tipo di risultato solo quando hai finito.
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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Indice

[modifica] Parametri

d -
durata da convertire
Original:
duration to convert
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[modifica] Valore di ritorno

d convertito in una durata di ToDuration tipo.
Original:
d converted to a duration of type ToDuration.
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[modifica] Note

La funzione non prende parte alla risoluzione di sovraccarico a meno ToDuration è un'istanza di 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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Fusione tra virgola mobile o tra durate durate interi in cui il periodo di sorgente è esattamente divisibile per il periodo di destinazione (ad esempio, ora a minuti) può essere eseguita implicitamente, non duration_cast è necessaria.
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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[modifica] Esempio

Questo esempio misura il tempo di esecuzione di una funzione
Original:
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";
}

Output:

f() took 1000 milliseconds