How does hashing work in C++17's unordered_map?

Can you explain how hashing works in C++17's unordered_map?

Sure! In C++17, unordered_map uses a hash function to map keys to buckets, allowing for average constant time complexity for lookups.

What is the default hash function used in unordered_map?

The default hash function is std::hash, which is specialized for various types like integers, strings, and pointers.

How can I provide a custom hash function?

You can provide a custom hash function by defining a struct with an operator() and passing it as a template argument to unordered_map.

Are there any performance considerations I should be aware of?

Yes, the choice of hash function and the load factor can significantly impact performance. A good hash function minimizes collisions.