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std::literals::chrono_literals::operator""h(3) | C++ Standard Libary | std::literals::chrono_literals::operator""h(3) |
NAME¶
std::literals::chrono_literals::operator""h - std::literals::chrono_literals::operator""h
Synopsis¶
Defined in header <chrono>
constexpr chrono::hours operator "" h(unsigned long long hrs);
(1) (since C++14)
constexpr chrono::duration</*unspecified*/, std::ratio<3600,1>>
(2) (since C++14)
operator "" h(long double hrs);
Forms a std::chrono::duration literal representing hours.
1) integer literal, returns exactly std::chrono::hours(hrs)
2) floating-point literal, returns a floating-point duration equivalent to
std::chrono::hours
Parameters¶
hrs - the number of hours
Return value¶
The std::chrono::duration literal.
Possible implementation¶
constexpr std::chrono::hours operator ""h(unsigned long
long h)
{
return std::chrono::hours(h);
}
constexpr std::chrono::duration<long double, ratio<3600,1>>
operator ""h(long double h)
{
return std::chrono::duration<long double, std::ratio<3600,1>>(h);
}
Notes¶
These operators are declared in the namespace
std::literals::chrono_literals, where
both literals and chrono_literals are inline namespaces. Access to these
operators
can be gained with using namespace std::literals, using namespace
std::chrono_literals, and using namespace std::literals::chrono_literals.
In addition, within the namespace std::chrono, the directive using namespace
literals::chrono_literals; is provided by the standard library, so that if a
programmer uses using namespace std::chrono; to gain access to the classes in
the
chrono library, the corresponding literal operators become visible as
well.
Example¶
// Run this code
#include <iostream>
#include <chrono>
int main()
{
using namespace std::chrono_literals;
auto day = 24h;
auto halfhour = 0.5h;
std::cout << "one day is " << day.count() <<
" hours\n"
<< "half an hour is " << halfhour.count() <<
" hours\n";
}
Output:¶
one day is 24 hours
half an hour is 0.5 hours
See also¶
constructor constructs new duration
(public member function of
std::chrono::duration<Rep,Period>)
2022.07.31 | http://cppreference.com |