How do I use unordered_map in C++17?

How do I use unordered_map in C++17?

In C++17, unordered_map is a part of the STL that allows you to store key-value pairs with fast access. You can include it by adding #include <unordered_map>.

What are the advantages of using unordered_map over map?

The main advantage of unordered_map is its average constant time complexity for lookups, insertions, and deletions, compared to logarithmic time for map.

Can you show me a simple example of unordered_map?

Sure! Here's a simple example:

#include <iostream>
#include <unordered_map>

int main() {
    std::unordered_map<std::string, int> umap;
    umap["apple"] = 1;
    umap["banana"] = 2;
    std::cout << "Apple: " << umap["apple"] << '\n';
    return 0;
}

Are there any specific use cases where unordered_map is preferred?

Yes, unordered_map is preferred when you need fast access to elements and don't require the elements to be sorted, such as counting occurrences of items.