std::literals::chrono_literals::operator""ms

Defined in header `<chrono>`
constexpr std::chrono::milliseconds operator""ms( unsigned long long ms );	(1)	(since C++14)
constexpr std::chrono::duration</unspecified/, std::milli> operator""ms( long double ms );	(2)	(since C++14)

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

1) Integer literal, returns exactly std::chrono::milliseconds(ms).

2) Floating-point literal, returns a floating-point duration equivalent to std::chrono::milliseconds.

Parameters

the number of milliseconds

Return value

The std::chrono::duration literal.

Possible implementation

constexpr std::chrono::milliseconds operator""ms(unsigned long long ms)
{
    return std::chrono::milliseconds(ms);
}
constexpr std::chrono::duration<long double, std::milli> operator""ms(long double ms)
{
    return std::chrono::duration<long double, std::milli>(ms);
}

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

#include <chrono>
#include <iostream>
 
int main()
{
    using namespace std::chrono_literals;
    constexpr auto d1{250ms};
    constexpr std::chrono::milliseconds d2{1s};
    std::cout << d1 << " = " << d1.count() << " milliseconds\n"
              << d2 << " = " << d2.count() << " milliseconds\n";
}

Output: