When working with lists or arrays in C++, it is often necessary to sort them in a specific order based on custom criteria. While the standard sorting functions in C++, such as std::sort(), are efficient for sorting values using default comparisons, they may not always be suitable for sorting custom literals.

In such cases, it is useful to define custom sorting literals to achieve the desired sorting behavior. In this blog post, we will explore how to implement custom sorting literals in C++.

Defining Custom Comparators

To implement custom sorting literals, we need to provide a custom comparator function or define a comparison operator. For this example, let’s consider sorting a list of strings based on their lengths.

#include <iostream>
#include <vector>
#include <algorithm>

bool compareStringLength(const std::string& str1, const std::string& str2) {
    return str1.length() < str2.length();
}

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

    std::sort(strings.begin(), strings.end(), compareStringLength);

    for (const auto& str : strings) {
        std::cout << str << " ";
    }

    return 0;
}

In the code above, we define a custom comparator function compareStringLength that compares two strings based on their lengths. The std::sort() function is then used with this custom comparator to sort the strings vector.

Using Lambda Functions

An alternative approach to defining custom comparators is by using lambda functions. Lambda functions provide a concise and inline way to define custom comparison criteria.

#include <iostream>
#include <vector>
#include <algorithm>

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

    std::sort(strings.begin(), strings.end(), [](const std::string& str1, const std::string& str2) {
        return str1.length() < str2.length();
    });

    for (const auto& str : strings) {
        std::cout << str << " ";
    }

    return 0;
}

In the above code snippet, we define a lambda function as the comparator directly within the std::sort() function call. The lambda function compares two strings based on their lengths.

Conclusion

Implementing custom sorting literals in C++ allows us to sort data according to our own custom criteria. Whether by defining custom comparator functions or using lambda functions, C++ provides flexibility in sorting data in a way that aligns with unique requirements.

By taking advantage of custom sorting literals, we can sort data in any manner we desire, expanding the capabilities of the standard sorting functions in C++.