Question

It was posted on this site how you could generate unique enum constants by doing the following:

enum _EXAMPLE
{
    LEFT = 'left',
    RIGHT = 'right'
    //etc
};

Ignoring the issue of validity, how are the numbers generated? More specifically, what technique is used? As I wish to try to build a function that emulates it for short strings.

Answer 1

'left' is a multicharacter literal (2.13.2/1 of C++03), it has type int.

It’s implementation-defined what integer value it actually has. In particular, there’s no guarantee that 'left' and 'right' aren’t equal, so you’re on to something of a loser using them in an enum.

For an example, though, GCC documents its behavior here: http://gcc.gnu.org/onlinedocs/gcc-4.6.1/cpp/Implementation_002ddefined-behavior.html#Implementation_002ddefined-behavior

'right' has five characters, and clearly it’s not possible for every 5-character string to have a different 32 bit value.