How to use complex number “i” in C++

Question

I am coding a simple DFT algorithm now and I want to use the complex number i in complex exponential. I saw somebody use #include and #include&

Answer 1

Another way is to use std::literals::complex_literals::operator""i after C++14:

#include 
#include 

int main() {
    using namespace std::complex_literals;
    auto c = 1.0 + 3.0i;
    std::cout << "c = " << c << '\n';
}

Output:

c = (1,3)