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

< cpp‎ | numeric‎ | complex
Defined in header <complex>
constexpr complex<double> operator""i( long double arg );
constexpr complex<double> operator""i( unsigned long long arg );
(1) (since C++14)
constexpr complex<float> operator""if( long double arg );
constexpr complex<float> operator""if( unsigned long long arg );
(2) (since C++14)
constexpr complex<long double> operator""il( long double arg );
constexpr complex<long double> operator""il( unsigned long long arg );
(3) (since C++14)

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.


[edit] Parameters

arg - the value of the imaginary number

[edit] Return value

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

[edit] 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 either:

  • using namespace std::literals,
  • using namespace std::complex_literals, or
  • 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.

Feature-test macro Value Std Feature
__cpp_lib_complex_udls 201309L (C++14) User-Defined Literals for std::complex

[edit] Possible implementation

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)};
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)};
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};

[edit] Example

#include <complex>
#include <iostream>
int main()
    using namespace std::complex_literals;
    std::complex<double> c = 1.0 + 1i;
    std::cout << "abs" << c << " = " << std::abs(c) << '\n';
    std::complex<float> z = 3.0f + 4.0if;
    std::cout << "abs" << z << " = " << std::abs(z) << '\n';


abs(1,1) = 1.41421
abs(3,4) = 5

[edit] See also

constructs a complex number
(public member function) [edit]
assigns the contents
(public member function) [edit]