How do I provide stable iteration order with std::unordered_map for large datasets?

To achieve a stable iteration order with std::unordered_map in C++, you can utilize std::vector to store the keys and then sort them when iterating. This approach provides a deterministic iteration order, especially useful for large datasets where consistent ordering is required.

Here's an example to illustrate this approach:


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

        int main() {
            std::unordered_map<std::string, int> my_map = {
                {"apple", 1},
                {"banana", 2},
                {"cherry", 3}
            };

            // Store keys in a vector
            std::vector<std::string> keys;
            for (const auto& pair : my_map) {
                keys.push_back(pair.first);
            }

            // Sort the keys
            std::sort(keys.begin(), keys.end());

            // Iterate in stable order
            for (const auto& key : keys) {
                std::cout << key << ": " << my_map[key] << std::endl;
            }

            return 0;
        }

How do I provide stable iteration order with std::unordered_map for large datasets?

Popular Topics

Recent Languages

How do I provide stable iteration order with std::unordered_map for large datasets?

Related Questions

Popular Topics

Recent Languages