add pure virtual

add interfaces like classes
add template example

CPlusPlus/intro/IComparable.h

@@ -0,0 +1,10 @@
+#pragma once
+#include <iostream>
+
+class IComparable
+{
+public:
+	IComparable() { std::cout << "IComparable() called" << std::endl; }
+	virtual ~IComparable() { std::cout << "~IComparable() called" << std::endl; }
+	virtual bool Compare(IComparable* pOther) = 0;
+};