adding the overloading example

lectures/13_operators/README.md

@@ -156,6 +156,12 @@ function of the Complex class. This is why stream operators are never member fun
 - Stream operators are either ordinary non-member functions (if the operators can do their work through the
 public class interface) or friend functions (if they need non public access).
 
+You can compile and run these three examples, in which the output stream operators are overloaded as a non-member function, a friend function, and a member function.
+
+- [Example 1](overloading_non_member.cpp)  
+- [Example 2](overloading_friend.cpp)  
+- [Example 3](overloading_member.cpp) - pay attention to the main function, does it surprise you?
+
 ## 13.10 Summary of Operator Overloading in C++
 
 - Unary operators that can be overloaded: + - * & ~ ! ++ -- -> ->*

lectures/13_operators/overloading_friend.cpp

@@ -0,0 +1,32 @@
+// Overloading the output stream operator as a friend function.
+
+#include <iostream>
+
+class MyClass {
+private:
+	int value;
+
+public:
+	MyClass(int val) : value(val) {}
+	friend std::ostream& operator<<(std::ostream& os, const MyClass& obj);
+
+	// getter function to access private member
+	int getValue() const {
+		return value;
+	}
+};
+
+// overload the output stream operator as a non-member function
+std::ostream& operator<<(std::ostream& os, const MyClass& obj) {
+	os << "Value: " << obj.value;
+	return os;
+}
+
+int main() {
+	MyClass obj(42);
+
+	// output the object using the overloaded operator
+	std::cout << obj << std::endl;
+
+	return 0;
+}

lectures/13_operators/overloading_member.cpp

@@ -0,0 +1,32 @@
+// Overloading the output stream operator as a member function.
+
+#include <iostream>
+
+class MyClass {
+private:
+	int value;
+
+public:
+	MyClass(int val) : value(val) {}
+
+	// getter function to access private member
+	int getValue() const {
+		return value;
+	}
+
+	// overload the output stream operator as a non-member function
+	std::ostream& operator<<(std::ostream& os) {
+		os << "Value: " << value;
+		return os;
+	}
+
+};
+
+int main() {
+	MyClass obj(42);
+
+	// output the object using the overloaded operator
+	obj << std::cout << std::endl;
+
+	return 0;
+}

lectures/13_operators/overloading_non_member.cpp

@@ -0,0 +1,31 @@
+// Overloading the output stream operator as a non-member function.
+
+#include <iostream>
+
+class MyClass {
+private:
+	int value;
+
+public:
+	MyClass(int val) : value(val) {}
+
+	// getter function to access private member
+	int getValue() const {
+		return value;
+	}
+};
+
+// overload the output stream operator as a non-member function
+std::ostream& operator<<(std::ostream& os, const MyClass& obj) {
+	os << "Value: " << obj.getValue();
+	return os;
+}
+
+int main() {
+	MyClass obj(42);
+
+	// output the object using the overloaded operator
+	std::cout << obj << std::endl;
+
+	return 0;
+}