Defined in header <chrono> | ||
---|---|---|
constexpr std::chrono::nanoseconds operator "" ns(unsigned long long nsec); | (1) | (since C++14) |
constexpr std::chrono::duration</*unspecified*/, std::nano> operator "" ns(long double nsec); | (2) | (since C++14) |
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 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
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 duration classes, the duration literal operators become visible as well.
Example
#include <iostream> #include <chrono> int main() { using namespace std::chrono_literals; auto d1 = 250ns; std::chrono::nanoseconds d2 = 1us; std::cout << "250ns = " << d1.count() << " nanoseconds\n" << "1us = " << d2.count() << " nanoseconds\n"; }
Output:
250ns = 250 nanoseconds 1us = 1000 nanoseconds
See also
constructs new duration (public member function of std::chrono::duration ) |
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