Solution Review: Subtract Two Complex Numbers

#include <iostream>
using namespace std;
// Structure to store complex number
struct complex_number {
  // Store real part of complex number
  double real;
  // Store imaginary part of complex number
  double imaginary;
};
// Function subtract
complex_number subtract(struct complex_number c1, struct complex_number c2) {
  // Declare a structure variable
  struct complex_number c;
  // Subtract real parts
  c.real = c1.real - c2.real;
  // Subtract imaginary parts
  c.imaginary = c1.imaginary - c2.imaginary;
  // Return structure variable
  return c;
}
// Function print_complex
void print_complex(struct complex_number c) {
  cout << c.real << " + ";
  cout << c.imaginary << " i ";
  cout << endl;
}
// Function main
int main() {
  // Declare structure variables
  struct complex_number c1, c2, c;
  // Initialize structure variable c1
  c1 = { -12.3, -67.4 };
  // Initialize structure variable c2
  c2 = { 34, 89 };
  // Print members of c1
  cout << "First complex number = " ;
  print_complex(c1);
  // Print members of c2
  cout << "Second complex number = " ;
  print_complex(c2);
  // Call subtract function and store its output in c
  c = subtract(c1, c2);
  // Print members of c
  cout << "First complex number - Second complex number = " ;
  print_complex(c);
}