When working with arrays or vectors in C++, there may be times when you need to sort elements based on a specific criterion that is not supported by the default sorting order. In such cases, you can use custom sorting literals to define your own sorting logic.

Sorting Based on Custom Criteria

To sort elements based on a custom criterion, you will need to define a function or a lambda expression that compares two elements and returns a bool value indicating their relative order.

Here’s an example that demonstrates sorting a vector of strings in descending order of their lengths:

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

bool compareLength(const std::string& s1, const std::string& s2) {
    return s1.length() > s2.length();
}

int main() {
    std::vector<std::string> strings = {"apple", "banana", "cherry", "date"};
    
    std::sort(strings.begin(), strings.end(), compareLength);
    
    for (const auto& str : strings) {
        std::cout << str << " ";
    }
    
    return 0;
}

In the above example, we define the compareLength function that compares two strings based on their lengths. The std::sort function is then used with compareLength as the comparison function to sort the vector in descending order of string lengths.

Sorting with Lambda Expressions

Alternatively, you can use lambda expressions to define the custom sorting logic inline without the need to define a separate function. Here’s an example that sorts a vector of integers in ascending order of their absolute values:

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

int main() {
    std::vector<int> numbers = {5, -3, 2, -8, 1};
    
    std::sort(numbers.begin(), numbers.end(), [](int a, int b) {
        return std::abs(a) < std::abs(b);
    });
    
    for (const auto& num : numbers) {
        std::cout << num << " ";
    }
    
    return 0;
}

In this example, the lambda expression [](int a, int b) { return std::abs(a) < std::abs(b); } is used as the comparison function to sort the vector of integers in ascending order of their absolute values.

Conclusion

Using custom sorting literals in C++ allows you to sort elements based on criteria that are not supported by the default sorting order. You can either define a separate comparison function or use lambda expressions to provide the sorting logic inline. This flexibility makes it easy to sort elements in a way that suits your specific needs.

Check out the official documentation on std::sort for more information on sorting in C++.

#cplusplus #sorting