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

 

C++

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std::complex

Member functions
complex::complex
complex::operator=
complex::real
complex::imag
complex::operator+=complex::operator-=complex::operator*=complex::operator/=
Non-member functions
operator+operator- operator+operator-operator*operator/ operator==operator!= operator<<operator>>	real imag abs arg norm conj proj (C++11) polar operator""ioperator""ifoperator""il (C++14)(C++14)(C++14)
Exponential functions
exp
log
log10
Power functions
pow
sqrt
Trigonometric functions
sin cos tan	asin (C++11) acos (C++11) atan (C++11)
Hyperbolic functions
sinh cosh tanh	asinh (C++11) acosh (C++11) atanh (C++11)

 

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

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

Output:

abs(1,1) = 1.41421

See also

(constructor)	constructs a complex number (public member function)
operator=	assigns the contents (public member function)
C documentation for I