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<complex> and #include<cmath>, and then they used the overloaded symbol I such as exp(2*I) . But it seems it doesn't work in my visual studio compiler. So, can anyone give a simple example of using complex exponential? Thanks!

Answer 1

Here is a short complete example:

#include <iostream>
#include <complex>
#include <cmath>

using namespace std;
typedef complex<double> dcomp;

int main() {
  dcomp i;
  dcomp a;
  double pi;
  pi = 2 * asin(1);
  i = -1;
  i = sqrt(i);
  a = exp(pi*i) + 1.+0i;
  cout << "i is " << i << "and Euler was right: exp(i pi) + 1 = " << a << endl;
} 

Tested with g++