Use CMake

.gitignore

@@ -0,0 +1,5 @@
+CMakeFiles/
+app
+CMakeCache.txt
+*.cmake
+Makefile

CMakeLists.txt

@@ -0,0 +1,7 @@
+cmake_minimum_required(VERSION 2.4)
+
+set(CMAKE_CXX_STANDARD 17)
+project(hello_world)
+
+include_directories(${PROJECT_SOURCE_DIR})
+add_executable(app main.cpp circle_shape.cpp rectangle_shape.cpp)

circle.h

@@ -1,5 +1,7 @@
-// circle.h
+#ifndef CIRCLE_H
+#define CIRCLE_H
 struct Circle
 {
     const double radius = 4.0;
-};
+};
+#endif

circle_shape.cpp

@@ -1,4 +1,5 @@
-// circle_shape.cpp
+#include "circle.h"
+
 namespace ShapeImpl
 {
 double area(const Circle &circle)
@@ -6,4 +7,4 @@ double area(const Circle &circle)
     double r = circle.radius;
     return 3.14 * r * r;
 }
-} // namespace ShapeImpl
+}

circle_shape.h

@@ -1,3 +1,5 @@
+#include "circle.h"
+
 namespace ShapeImpl
 {
 double area(const Circle &circle);

main.cpp

@@ -12,7 +12,7 @@ int main()
 {
     vector<Shape> geometries;
     geometries.emplace_back(Circle());
-    // geometries.emplace_back(Rectangle());
+    geometries.emplace_back(Rectangle());
 
     for (const auto &shape : geometries)
     {

rectangle_shape.cpp

@@ -1,9 +1,9 @@
+#include "rectangle.h"
 
-// rectangle_shape.cpp
 namespace ShapeImpl
 {
 double area(const Rectangle &rectangle)
 {
     return rectangle.width * rectangle.height;
 }
-} // namespace ShapeImpl
+}