Question

Possible Duplicate:
C: Where is union practically used?

I know the concept of union but I don’t see the actual case in real world coding that I should use union data structure. I will be very appreciated if you guys can give me some examples or tutorials that shows cases using union properly.

Thanks in advance.

Answer 1

Where I use it constantly: parsing a configuration file I store all values in a union data type. E.g. when values can be int types or strings, I would use a data structure as follows:

struct cval_s {
  short type;
  union {
    int ival;
    char *cval;
  } val;
};

In complexer problems, I use them, too. E.g. once I wrote an interpreter for an easy scripting language, and a value in this language was represented by a struct containing a union.