Are C++ std::hash implementations always deterministic?

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Are C++ std::hash implementations always deterministic?



I know that std::hash<T> are implementation dependent, but are they supposed to be deterministic?


std::hash<T>



I know if I ran the std::hash<T> function on a value in the same process multiple times, I would get the same output. However, if I restarted the process, would I get the same value? Is there a seed that is used for std::hash? Does it depend on the compiler version, or some other factor?


std::hash<T>



Is there a guarantee that with an input X I will always get output Y regardless of when the process running was started, the machine, or the compiler version?


X


Y









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