adding overloading operator example

lectures/09_iterators_linked_lists/README.md

@@ -202,6 +202,59 @@ int main() {
 }
 ```
 
+### List Sort Example - Sorting Class Objects, via Overloading the Less Than Operator
+
+The following [example](list_sort_objects2.cpp) also demonstrates how to call the list sort function to sort a list which contains class objects.
+
+
+```cpp
+#include <iostream>
+#include <list>
+#include <string>
+
+// Define a simple class representing a person
+class Person {
+public:
+    std::string name;
+    int age;
+
+    // Constructor
+    Person(std::string name, int age) : name(name), age(age) {}
+
+    // Overload the < operator for sorting
+    bool operator<(const Person& other) const {
+        // Compare based on age
+        return age < other.age;
+    }
+};
+
+int main() {
+    // Create a list of Person objects
+    std::list<Person> people = {
+        {"Alice", 25},
+        {"Bob", 30},
+        {"Charlie", 20}
+    };
+
+    // Print the original list
+    std::cout << "Original list:" << std::endl;
+    for (const auto& person : people) {
+        std::cout << person.name << " (" << person.age << ")" << std::endl;
+    }
+
+    // Sort the list of Person objects
+    people.sort();
+
+    // Print the sorted list
+    std::cout << "\nSorted list:" << std::endl;
+    for (const auto& person : people) {
+        std::cout << person.name << " (" << person.age << ")" << std::endl;
+    }
+
+    return 0;
+}
+```
+
 ## 9.7 Erase & Iterators
 
 STL lists and vectors each have a special member function called erase. In particular, given list of ints s,

lectures/09_iterators_linked_lists/list_sort_objects2.cpp

@@ -0,0 +1,45 @@
+#include <iostream>
+#include <list>
+#include <string>
+
+// Define a simple class representing a person
+class Person {
+public:
+    std::string name;
+    int age;
+
+    // Constructor
+    Person(std::string name, int age) : name(name), age(age) {}
+
+    // Overload the < operator for sorting
+    bool operator<(const Person& other) const {
+        // Compare based on age
+        return age < other.age;
+    }
+};
+
+int main() {
+    // Create a list of Person objects
+    std::list<Person> people = {
+        {"Alice", 25},
+        {"Bob", 30},
+        {"Charlie", 20}
+    };
+
+    // Print the original list
+    std::cout << "Original list:" << std::endl;
+    for (const auto& person : people) {
+        std::cout << person.name << " (" << person.age << ")" << std::endl;
+    }
+
+    // Sort the list of Person objects
+    people.sort();
+
+    // Print the sorted list
+    std::cout << "\nSorted list:" << std::endl;
+    for (const auto& person : people) {
+        std::cout << person.name << " (" << person.age << ")" << std::endl;
+    }
+
+    return 0;
+}