add example of state pattern in C++

cpp/patterns/state/main.cpp

@@ -0,0 +1,31 @@
+
+#include <iostream>
+
+#include "state.hpp"
+
+int main(const int argc, const char * argv[]) {
+  Car * testCar = new Car;
+  testCar->report();
+
+  // Test transition from Stopped->Running
+  testCar->Start();
+  testCar->report();
+
+  // Test transition from Running->Stopped
+  testCar->Stop();
+  testCar->report();
+
+  // Test transition from Stopped->Broken
+  testCar->Smash();
+  testCar->report();
+
+  std::cout << "\nTesting burning state...\n";
+
+  Car *newCar = new Car;
+  newCar->report();
+
+  // Test transition from Stopped->Running->Burning
+  newCar->Start();
+  newCar->Smash();
+  newCar->report();
+}