What are some use cases for unordered maps in C++?

What are some use cases for unordered maps in C++?

Unordered maps in C++ are great for scenarios where you need fast lookups, like caching data or counting occurrences.

Can you give me an example of using an unordered map for counting word frequencies?

Sure! You can use an unordered map to store words as keys and their frequencies as values. For example:

#include <iostream>
#include <unordered_map>
#include <string>

int main() {
    std::unordered_map<std::string, int> wordCount;
    std::string word;
    while (std::cin >> word) {
        wordCount[word]++;
    }
    for (const auto& pair : wordCount) {
        std::cout << pair.first << ': ' << pair.second << '\n';
    }
}

This code counts how many times each word appears in the input.

What are the performance benefits of using unordered maps?

Unordered maps provide average constant time complexity for insertions, deletions, and lookups, making them very efficient for large datasets.

Are there any drawbacks to using unordered maps?

Yes, unordered maps use more memory than ordered maps due to their underlying hash table structure, and they don't maintain order.