also interest

http://stackoverflow.com/questions/1220046/in-c-how-to-get-md5-hash-of-a-file

Using Crypto++, you could do the following:

#include 
#include 

SHA256 sha;
while ( !f.eof() ) {
   char buff[4096];
   int numchars = f.read(...);
   sha.Update(buff, numchars);
}
char hash[size];
sha.Final(hash);
cout  hash endl;