Re: Why not unions

"Rob Thorpe" <robert.thorpe@xxxxxxxxxxxx> wrote in message
news:1122490853.570267.241310@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
[snip]
> In C there are two main uses of unions:
> 1. To save space by using a single location to store many types of
> data.
[snip]
> union bar {
> int x;
> double y;
> }
> struct foo {
> enum thing what_it_is;
> union bar b;
> }
>
> foo.what_it_is describes what is in the union b, it could have values
> DOUBLE or INT for example.
>
> It's only worth making this a union if we need the space. If we don't
> then we could use:
>
> struct foo {
> enum thing what_it_is;
> int x;
> double y;
> char *z;
> }
>
> Which is simpler and easier to check.

Why do you think that?

FWIW, I would generally use an "unnamed" (not sure if that is the correct
term) union type declared inside the struct:

struct foo {
enum thing what_it_is;
union {
int x;
/* etc */
} b;
};

Alex


.

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