In C++, we often encounter scenarios where we want to sort a collection of objects in a custom order, different from the default sorting behavior. One way to achieve this is by using custom sorting literals.

1. Defining a custom sorting literal

To define a custom sorting literal, we need to overload the comparison operator (<) for our object type. We define a function that takes two objects of our type and returns a boolean value indicating whether the first object should be sorted before the second object.

Here’s an example of defining a custom sorting literal for a class Person based on their age:

class Person {
public:
    std::string name;
    int age;

    Person(const std::string& name, int age) : name(name), age(age) {}

    bool operator<(const Person& other) const {
        // Custom sorting logic based on age
        return age < other.age;
    }
};

2. Sorting objects using the custom sorting literal

Once we have defined the custom sorting literal for our object type, we can use it with sorting algorithms like std::sort from the C++ standard library.

Here’s an example of how to sort a vector of Person objects using the custom sorting literal:

std::vector<Person> people;
people.push_back(Person("Alice", 25));
people.push_back(Person("Bob", 30));
people.push_back(Person("Claire", 20));

std::sort(people.begin(), people.end());

After the sorting operation, the vector people will be sorted in ascending order based on the age of each person.

3. Using custom sorting literals with complex sorting criteria

Custom sorting literals can be used to define complex sorting criteria based on multiple attributes of an object. In such cases, the comparison operator should implement the desired sorting logic based on the attributes.

For example, consider a class Product with attributes name, price, and quantity. We can define a custom sorting literal based on the price and quantity of each product:

class Product {
public:
    std::string name;
    double price;
    int quantity;

    Product(const std::string& name, double price, int quantity)
        : name(name), price(price), quantity(quantity) {}

    bool operator<(const Product& other) const {
        // Custom sorting logic based on price and quantity
        if (price != other.price)
            return price < other.price;
        else
            return quantity < other.quantity;
    }
};

In this example, the Product objects will be sorted first based on the price and then based on the quantity, in ascending order for both attributes.

Conclusion

Custom sorting literals allow us to define our own sorting rules for objects in C++. By overloading the comparison operator, we can implement complex sorting logic based on the attributes of our object types. This provides flexibility and customization options when sorting collections of objects.

#cpp #sorting