What is the best way to generate a unique unsigned integer from a string in c++?

Question

I don't need code (you can provide examples in code if you wish) but I would like the theory.

Let's pretend I have the following function:

UINT GenerateID(const char * string);

I would like the function's result to look completely random. I understand that it is impossible to be unique, but that is the best way I could explain my desire.

GenerateID("123"); //Could result in 999
GenerateID("123"); //Must also result in 999
GenerateID("124"); //Should result in something completely different

When attempting this myself, the results always have roughly the same amount of digits.

Answer 1

You're looking for a hash function. A hash function takes an input of arbitrary length and converts it to a unique number (often hexadecimal).

Check this page out for an example of how the SHA-1 hash works: http://hash.online-convert.com/sha1-generator

Answer 2

Have you looked into std::hash ?

http://en.cppreference.com/w/cpp/utility/hash