C++: How to compute hash value from several hashable members?

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Suppose I have a C++ class

class T {
  Type1 member1;
  Type2 member2;
  Type3 member3;
  unsigned long hash() {
    // How to implement?
  }
};

Assuming each member hash a hash function member.hash(). What is the best way to implement the hash function of class T? Java has a HashCodeBuilder class specific for this task, is there a counterpart in C++?

I know one possible solution could be something like

member1.hash() + member2.hash() * 17 + member3.hash() * 37

Is this generally a good hash function? And how should I choose the constants 17, 37, etc., esp. if I more than 3 members?

Another minor question is assuming one of my member is primitive type (int, float, string, etc.), how should I generate a hash value from it?

Thanks a lot!

asked 30 secs ago

Ying Xiong

111

C++: How to compute hash value from several hashable members?