How do I customize hashing and equality with std::list?

In C++, the std::list is a doubly-linked list that provides various functionalities such as insertion, deletion, and traversal. However, it does not support hashing or equality comparison out of the box. To customize hashing and equality for elements in a std::list, you can define your own hash function and equality operator.

Here's how you can achieve this:


    #include <iostream>
    #include <list>
    #include <unordered_set>
    
    struct CustomType {
        int id;
        std::string name;

        // Equality operator
        bool operator==(const CustomType &other) const {
            return id == other.id && name == other.name;
        }
    };

    struct CustomHash {
        std::size_t operator()(const CustomType &ct) const {
            return std::hash()(ct.id) ^ std::hash<:string>()(ct.name);
        }
    };

    int main() {
        std::list myList = { {1, "Alice"}, {2, "Bob"}, {3, "Charlie"} };

        // Using unordered set to show hashing and equality.
        std::unordered_set mySet(myList.begin(), myList.end());

        // Iterate and display elements
        for (const auto &element : mySet) {
            std::cout << "ID: " << element.id << ", Name: " << element.name << std::endl;
        }

        return 0;
    }

C++ std::list hashing equality custom hash function C++ list example

How do I customize hashing and equality with std::list?

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How do I customize hashing and equality with std::list?

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