std::litera...perator""us(3)

bestie, welcome to the C++ Standard Libary manual ✨ this page is all about the std::literals::chrono_literals::operator""us operator — the literal that makes microseconds happen 💅

💖 NAME 💖

std::literals::chrono_literals::operator""us — std::literals::chrono_literals::operator""us 🫶

✨ Synopsis ✨

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

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. periodt ✨

🛠️ 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 🧠

Okay so this operator is declared in the namespace std::literals::chrono_literals, where both literals and chrono_literals are inline namespaces 👑. You can get access to this operator 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 = 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 👀

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

mwah 💋 this page comes from http://cppreference.com, dated 2024.06.10, and it's the std::litera...perator""us(3) page — periodt, bestie 🫶✨