Hashing pointers as Keys for unordered_map in C++ STL

问题

I posted a similar quetion regarding using pointers as Keys on maps in C++ STL. How are pointers hashed in unordered_maps when used as Keys. More specifically if I define:

std::unordered_map< CustomClass*, int > foo;

Would the default C++ std::hash implementation work to handle these pointers? Is it safe to use? Is this good practice?

回答1:

std::hash<T*> is defined but the details of how it operates are implementation dependent. It will certainly be safe to use, and I'd consider it good practice - as long as it's the pointer you need as the key, and not the object contents itself.

来源：https://stackoverflow.com/questions/25124923/hashing-pointers-as-keys-for-unordered-map-in-c-stl