add forward declaration examples

add classes

CPlusPlus/Classes/Entity.h

@@ -0,0 +1,19 @@
+#pragma once
+#include <string>
+
+namespace MyNamespace
+{
+	class Entity
+	{
+	public:
+		Entity(); // constructor declaration
+		Entity(std::string n);
+
+		virtual std::string ToString() { return "Entity"; } // defined
+		void setName(std::string n) { _name = n; } // defined
+		std::string getName() { return _name; }
+
+	protected:
+		std::string _name = "";
+	}; // IMPORTANT: semicolon at the end 
+}