How to hash std::string?

Question

I'm making a little utility to help me remember passwords by repetition. I'd like to enter password to be remembered only once every day and not before each session. Of course, I wouldn't store a password itself, but would gladly store its hash.

So, what are the easiest ways to get a hash from std::string using the C++ Standard Library?

Answer 1

For a quick solution involving no external libraries, you can use hash<std::string> to hash strings. It's defined by including the header files hash_map or unordered_map (or some others too).

#include <string> #include <unordered_map>  hash<string> hasher;  string s = "heyho";  size_t hash = hasher(s); 

If you decide you want the added security of SHA, you don't have to download the large Crypto++ library if you don't need all its other features; there are plenty of standalone implementations on the internet, just search for "sha implementation c++".

Answer 2

using c++11, you can:

#include <string> #include <unordered_map>  std::size_t h1 = std::hash<std::string>{}("MyString"); std::size_t h2 = std::hash<double>{}(3.14159); 

see more here.