std::chrono::duration<Rep,Period>::operator=

 

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std::chrono::duration

成员函数
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%=
非成员函数
operator+operator-operator*operator/operator% operator==operator!=operator<operator<=operator>operator>=operator<=> (直到 C++20)(C++20) operator<< (C++20)	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) from_stream (C++20)
辅助类
common_type treat_as_floating_point      duration_values	formatter<std::chrono::duration> (C++20) hash<std::chrono::duration> (C++26)

 

duration& operator=( const duration &other ) = default;		(自 C++11 起)

将一个 duration 的内容赋值给另一个。

参数

other

-

要复制的 duration

示例

运行此代码

#include <chrono>
#include <iostream>
 
int main()
{
    using namespace std::chrono_literals;
 
    std::chrono::hours z_hours{};
    std::chrono::seconds z_seconds{};
 
    z_hours = 2h; // ok, no conversion needed
 
    z_seconds = z_hours;
    // First, the converting ctor is used to create a temporary object of `lhs`s type.
    // This ctor implicitly invokes the casting function
    // chrono::duration_cast<std::seconds>(z_hours). The resulting `rhs` rvalue
    // has the same type as `lhs`, and the `operator=` finally performs the assignment.
 
    std::cout << "hours: " << z_hours.count() << '\n';
    std::cout << "seconds: " << z_seconds.count() << '\n';
 
    z_seconds -= 42s;
 
//  z_hours = z_seconds; // compile-time error (which is good): incompatible types.
    // The library avoids the implicit cast to prevent a potential precision loss.
 
    z_hours = std::chrono::duration_cast<std::chrono::hours>(z_seconds); // ok
    z_hours = std::chrono::duration_cast<decltype(z_hours)>(z_seconds);  // ditto
 
    std::cout << "hours: " << z_hours.count() << '\n';
    std::cout << "seconds: " << z_seconds.count() << '\n';
 
    std::chrono::duration<double, std::ratio<3600>> z2_hours{};
 
    z2_hours = z_seconds; // ok, no truncation, implicit cast
 
    std::cout << "hours: " << z2_hours.count() << '\n';
}

输出

hours: 2
seconds: 7200
hours: 1
seconds: 7158
hours: 1.98833

另请参阅

(构造函数)

构造新的 duration (公共成员函数)