What are the best practices for using unordered maps in C++11?

What are the best practices for using unordered maps in C++11?

When using unordered maps in C++11, consider the following best practices: 1. Use appropriate hash functions. 2. Reserve space if the size is known. 3. Avoid unnecessary copies by using emplace or move semantics.

Can you explain why reserving space is important?

Reserving space in an unordered map can improve performance by reducing the number of reallocations needed as elements are added. This can lead to faster insertions.

What hash functions are recommended?

For unordered maps, you can use the default hash function provided by the STL, or you can define your own if you have specific needs. Just ensure it's efficient and minimizes collisions.

How do I handle collisions in unordered maps?

C++11's unordered map handles collisions internally using chaining. However, you can also implement your own collision resolution strategy if needed.