Custom sorting literals in C++

23 Oct 2023

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Sorting is a fundamental operation in programming, and most programming languages offer built-in sorting functionality. However, there may be cases where you need to sort objects in a custom order that is not supported by the default sorting algorithms.

In C++, you can achieve custom sorting by providing a custom comparison function or by overloading the comparison operators. But what if you want to sort objects using your own custom literal order, such as sorting weekdays in a specific order or sorting book genres alphabetically with some exceptions?

In this article, we will explore how to implement custom sorting literals in C++ to achieve fine-grained control over the sorting order.

Custom Sorting with std::sort

The std::sort function in C++ is a convenient way to sort elements in a container. By providing a custom comparison function, you can define your own sorting order.

#include <algorithm>
#include <vector>

// Custom comparison function
bool customComparison(const std::string& s1, const std::string& s2) {
    // Implement your custom sorting logic here
}

int main() {
    std::vector<std::string> words = { "apple", "banana", "cherry" };

    std::sort(words.begin(), words.end(), customComparison);

    // Print sorted words
    for (const auto& word : words) {
        std::cout << word << " ";
    }
    std::cout << std::endl;

    return 0;
}

In the customComparison function, you can define your own logic to compare two elements. For example, you can implement a custom sorting order based on the length of the strings or any other criteria required by your application.

Custom Sorting Literals

To implement custom sorting literals, you can take advantage of C++’s operator overloading capabilities. By overloading the comparison operators (<, >, <=, >=, ==, !=), you can define the desired ordering for your objects.

#include <iostream>
#include <vector>

enum class Weekday {
    Sunday,
    Monday,
    Tuesday,
    Wednesday,
    Thursday,
    Friday,
    Saturday
};

// Overload comparison operators for Weekday
bool operator<(const Weekday& lhs, const Weekday& rhs) {
    // Implement custom ordering for weekdays
}

int main() {
    std::vector<Weekday> days = { Weekday::Friday, Weekday::Monday, Weekday::Sunday };

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

    // Print sorted weekdays
    for (const auto& day : days) {
        std::cout << static_cast<int>(day) << " ";
    }
    std::cout << std::endl;

    return 0;
}

In this example, we define an enumeration Weekday with the days of the week. We then overload the < operator to define the custom ordering for weekdays. You can implement the comparison logic based on the desired sorting order.

Conclusion

Implementing custom sorting literals in C++ allows you to specify a custom ordering for your objects beyond the default sorting algorithms. By providing a custom comparison function or overloading the comparison operators, you can achieve fine-grained control over the sorting order of your data.

Whether you need to sort weekdays, book genres, or any other objects in a specific order, C++ provides the flexibility to achieve your desired sorting order. Custom sorting not only enhances the readability and usability of your code but also allows you to tailor the sorting behavior to the requirements of your application.

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