NAME¶

std::literals::chrono_literals::operator""ns - std::literals::chrono_literals::operator""ns

Synopsis¶

Defined in header <chrono>
constexpr std::chrono::nanoseconds (1) (since C++14)
operator""ns( unsigned long long nsec );
constexpr std::chrono::duration</*unspecified*/, std::nano> (2) (since C++14)
operator""ns( long double nsec );

Forms a std::chrono::duration literal representing nanoseconds.

1) Integer literal, returns exactly std::chrono::nanoseconds(nsec).
2) Floating-point literal, returns a floating-point duration equivalent to
std::chrono::nanoseconds.

Parameters¶

nsec - the number of nanoseconds

Return value¶

The std::chrono::duration literal.

Possible implementation¶

constexpr std::chrono::nanoseconds operator""ns(unsigned long long ns)
{
return std::chrono::nanoseconds(ns);
}
constexpr std::chrono::duration<long double, std::nano> operator""ns(long double ns)
{
return std::chrono::duration<long double, std::nano>(ns);
}

Notes¶

This operator is declared in the namespace std::literals::chrono_literals, where
both literals and chrono_literals are inline namespaces. Access to this operator can
be gained with:

* using namespace std::literals,
* using namespace std::chrono_literals, or
* 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 <chrono>
#include <iostream>

int main()
{
using namespace std::chrono_literals;
auto d1{250ns};
std::chrono::nanoseconds d2{1us};
std::cout << d1 << " = " << d1.count() << " nanoseconds\n"
<< d2 << " = " << d2.count() << " nanoseconds\n";
}

Output:¶

250ns = 250 nanoseconds
1000ns = 1000 nanoseconds

See also¶

constructor constructs new duration
(public member function of std::chrono::duration<Rep,Period>)