How to hash any type in C++

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How to hash any type in C++. When I was writing my own map, I realized that I can't write hash function for all combinations of types (int, string, vector<int>, vector<vector<...)

do you="" have="" any="" idea?

<b="">I don't want to find an inner function. I want to create my own to figure out how it works.

What I have tried:

I had an idea to hash not data, but their addresses. But addresses can be changed, so I've got stuck.

Posted 2-Jan-22 0:28am

temchik_ggg

Updated 2-Jan-22 21:02pm

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Richard MacCutchan 2-Jan-22 7:07am

There are many ways to hash data, which google will find for you. Remember all data is just a sequence of bytes, however it may be interpreted.

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KarstenK · Answer 1 · 2022-01-02T21:02:00

Solution 1

You need to hash all data of any class object. And you need to overwrite it in every class which you are designing to get a unique hash.

The C++ vector has already some hash support.

If a hash isnt unique - it isnt a hash. There is no way around it.

Posted 2-Jan-22 21:02pm

KarstenK

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Greg Utas 3-Jan-22 7:42am

Many containers that use hashing allow for collisions.

KarstenK 3-Jan-22 9:54am

I wont use such implementations. Hash is for lookup and I wont risk false positives.

Greg Utas 3-Jan-22 10:19am

See std::unordered_multimap.

How to hash any type in C++

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How to hash any type in C++

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