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

I get this question recently as well and find a easy way for future reader:

Just use library like the following

#include 
#include 
using namespace std ;

int main(int argc, char* argv[])
{
    const   complex i(0.0,1.0);    
    cout << i << endl ;

    return(0) ;
}