Std::literals::complex_literals::operator""i,operator""if,operator""il (3) Linux Manual Page

std::literals::complex_literals::operator""i,operator""if,operator""il – std::literals::complex_literals::operator""i,operator""if,operator""il

Synopsis

Defined in header<complex>

    constexpr complex<double> operator""i(long double arg);
(1)(since C++ 14)

    constexpr complex<double>
    operator""i(unsigned long long arg);

constexpr complex<float> operator""if(long double arg);
(2)(since C++ 14)

    constexpr complex<float>
    operator""if(unsigned long long arg);

constexpr complex<long double> operator""il(long double arg);
(3)(since C++ 14)

    constexpr complex<long double>
    operator""il(unsigned long long arg);

Forms a std::complex literal representing an imaginary number.
1) forms a literal std::complex<double> with the real part zero and imaginary part arg
2) forms a literal std::complex<float> with the real part zero and imaginary part arg
3) forms a literal std::complex<long double> with the real part zero and imaginary part arg

Parameters

arg – the value of the imaginary number

Return value

The std::complex literal with the real part zero and imaginary part arg

Notes

These operators are declared in the namespace std::literals::complex_literals, where both literals and complex_literals are inline namespaces. Access to these operators can be gained with using namespace std::literals, using namespace std::complex_literals, and using namespace std::literals::complex_literals.
Even though if is a keyword in C++, it is a ud-suffix of the literal_operator of the form operator ""if and in the literal expressions such as 1if or 1.0if because it is not separated by whitespace and is not a standalone token.

Possible implementation

First version

  constexpr std::complex<double> operator""i(unsigned long long d)
  {
      return std::complex<double>{0.0, static_cast<double>(d)};
  }
  constexpr std::complex<double> operator""i(long double d)
  {
      return std::complex<double>{0.0, static_cast<double>(d)};
  }

Second version

  constexpr std::complex<float> operator""if(unsigned long long d)
  {
      return std::complex<float>{0.0f, static_cast<float>(d)};
  }
  constexpr std::complex<float> operator""if(long double d)
  {
      return std::complex<float>{0.0f, static_cast<float>(d)};
  }

Third version

  constexpr std::complex<long double> operator""il(unsigned long long d)
  {
      return std::complex<long double>{0.0L, static_cast<long double>(d)};
  }
  constexpr std::complex<long double> operator""il(long double d)
  {
      return std::complex<long double>{0.0L, d};
  }

Example

// Run this code

#include <iostream>

#include <complex>
int main()

{
    using namespace std::complex_literals;
    std::complex<double> c = 1.0 + 1i;
    std::cout << "abs" << c << " = " << abs(c) << '\n';
}

Output:

abs(1,1) = 1.41421

std::literals::complex_literals::operator””i,operator””if,operator””il (3) Linux Manual Page