14.5. OutputΒΆ

As usual when we define a new class, we want to be able to output objects in a human-readable form. For complex_number objects, we could use two functions:

void complex_number::print_cartesian ()
{
  std::cout << get_real() << " + " << get_imag() << "i" << std::endl;
}

void complex_number::print_polar ()
{
  std::cout << get_mag() << " e^ " << get_theta() << "i" << std::endl;
}

The nice thing here is that we can output any complex_number object in either format without having to worry about the representation. Since the output functions use the accessor functions, the program will compute automatically any values that are needed.

The following code creates a complex_number object using the second constructor. Initially, it is in Cartesian format only. When we invoke print_cartesian it accesses real and imag without having to do any conversions.

complex_number c1 (2.0, 3.0);

c1.print_cartesian();
c1.print_polar();

When we invoke print_polar, and print_polar invokes get_mag, the program is forced to convert to polar coordinates and store the results in the instance variables. The good news is that we only have to do the conversion once. When print_polar invokes get_theta, it will see that the polar coordinates are valid and return theta immediately.

The output of this code is:

2 + 3i
3.60555 e^ 0.982794i

The active code below uses the print functions for complex_number objects. Feel free to modify the code and experiment around!

Example c192_fourteensix
 1#include <iostream>
 2#include <cmath>
 3
 4class complex_number
 5{
 6  double real = 0.0, imag = 0.0;
 7  double mag = 0.0, theta = 0.0;
 8  bool cartesian, polar;
 9
10public:
11  complex_number ();
12  complex_number (double r, double i);
13  void calculate_cartesian ();
14  double get_real ();
15  double get_imag ();
16  void calculate_polar ();
17  double get_mag ();
18  double get_theta ();
19  void print_cartesian ();
20  void print_polar ();
21};
22
23int main() {
24  complex_number c1 (2.0, 3.0);
25  c1.print_cartesian();
26  c1.print_polar();
27}

What is the correct output of the code below?

int main() {
  Complex c1 (3.0, 4.0);
  // c1.printCartesian();
  c1.printPolar();
}