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

ms

-

the number of milliseconds

Return value

The std::chrono::duration literal.

Possible implementation

constexpr std::chrono::milliseconds operator ""ms(unsigned long long ms)
{
    return 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

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 d1 = 250ms;
    std::chrono::milliseconds d2 = 1s;
    std::cout << "250ms = " << d1.count() << " milliseconds\n"
              << "1s = " << d2.count() << " milliseconds\n";
}

Output:

250ms = 250 milliseconds
1s = 1000 milliseconds

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