What are some use cases for std::map in C++?

What are some use cases for std::map in C++?

std::map is useful for storing key-value pairs where keys are unique. Common use cases include implementing dictionaries, counting occurrences of items, and maintaining sorted data.

Can you give me an example of using std::map to count word frequencies?

Sure! You can use std::map to count word frequencies like this:

#include <iostream>
#include <map>
#include <string>

int main() {
    std::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 reads words from input and counts their occurrences.

What are the performance characteristics of std::map?

std::map is implemented as a balanced binary tree, providing O(log n) time complexity for insertions, deletions, and lookups. However, if you need faster access and don't require sorted keys, consider using std::unordered_map.

Are there any limitations to using std::map?

Yes, std::map requires keys to be comparable, which can be a limitation if your key type doesn't support comparison operators. Additionally, it has higher memory overhead compared to other data structures like std::unordered_map.