Getting ready

We will compile an example program to calculate the area of different geometric shapes. The code has a main function in a file called compute-areas.cpp:

#include "geometry_circle.hpp"
#include "geometry_polygon.hpp"
#include "geometry_rhombus.hpp"
#include "geometry_square.hpp"

#include <cstdlib>
#include <iostream>

int main() {
  using namespace geometry;

  double radius = 2.5293;
  double A_circle = area::circle(radius);
  std::cout << "A circle of radius " << radius << " has an area of " << A_circle
            << std::endl;

  int nSides = 19;
  double side = 1.29312;
  double A_polygon = area::polygon(nSides, side);
  std::cout << "A regular polygon of " << nSides << " sides of length " << side
            << " has an area of " << A_polygon << std::endl;

  double d1 = 5.0;
  double d2 = 7.8912;
  double A_rhombus = area::rhombus(d1, d2);
  std::cout << "A rhombus of major diagonal " << d1 << " and minor diagonal " << d2
            << " has an area of " << A_rhombus << std::endl;

  double l = 10.0;
  double A_square = area::square(l);
  std::cout << "A square of side " << l << " has an area of " << A_square
            << std::endl;

  return EXIT_SUCCESS;
}

The implementations of the various functions are contained in other files: each geometric shape has a header file and a corresponding source file. In total, we have four header files and five source files to compile:

.
├── CMakeLists.txt
├── compute-areas.cpp
├── geometry_circle.cpp
├── geometry_circle.hpp
├── geometry_polygon.cpp
├── geometry_polygon.hpp
├── geometry_rhombus.cpp
├── geometry_rhombus.hpp
├── geometry_square.cpp
└── geometry_square.hpp

We will not provide listings for all these files but rather refer the reader to https://github.com/dev-cafe/cmake-cookbook/tree/v1.0/chapter-01/recipe-08.