std::literals::chrono_literals::operator""us

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operator""us
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Helper classes
Defined in header <chrono>
constexpr std::chrono::microseconds
    operator""us( unsigned long long us ) ;
(1) (since C++14)
constexpr std::chrono::duration < /*unspecified*/, std::micro >
    operator""us( long double us ) ;
(2) (since C++14)

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

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

Parameters

us - the number of microseconds

Return value

The std::chrono::duration literal.

Possible implementation

constexpr std::chrono::microseconds operator""us(unsigned long long us)
{
    return std::chrono::microseconds(us);
}
constexpr std::chrono::duration<long double, std::micro> operator""us(long double us)
{
    return std::chrono::duration<long double, std::micro>(us);
}

Notes

This operator is declared in the namespace std::literals::chrono_literals, where both literals and chrono_literals are inline namespaces

  • 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

Example

Run this code
#include <chrono>
#include <iostream>
 
int main()
{
    using namespace std::chrono_literals;
    auto d1 = 250us;
    std::chrono::microseconds d2 = 1ms;
    std::cout << d1 << " = " << d1.count() << " microseconds\n"
              << 1ms << " = " << d2.count() << " microseconds\n";
}

Output: 

250us = 250 microseconds
1ms = 1000 microseconds

See also

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