What are the differences between standard hash functions in C++11?

What are the differences between standard hash functions in C++11?

C++11 introduced several standard hash functions, primarily in the <functional> header. The main ones are std::hash, which provides a default hash function for various types, and specialized hash functions for specific types like strings and pointers.

Can you explain how std::hash works for strings?

Sure! std::hash for strings uses a combination of algorithms to generate a hash value. It typically involves processing the string's characters and applying bitwise operations to ensure a uniform distribution of hash values.

Are there any performance considerations when using std::hash?

Yes, performance can vary based on the type of data being hashed. For large datasets, the efficiency of the hash function can impact overall performance, so it's important to choose the right hash function for your use case.

What about custom hash functions? How do I implement one?

You can implement a custom hash function by defining a struct with an operator() that takes your data type as input and returns a size_t hash value. This allows you to tailor the hashing process to your specific needs.