A union is declared in the same way as a structure. It has a list
of members, as in the example below:
union int_or_float
{
int int_member;
float float_member;
};
Declaring union variables is similar to declaring structure variables:
union int_or_float my_union1, my_union2;
Just like structures, the members of unions can be accessed with the
. and -> operators. However, unlike structures, the
variables my_union1 and my_union2 above can be treated as
either integers or floating-point variables at different times during
the program. For example, if you write my_union1.int_member =
5;, then the program sees my_union1 as being an integer. (This
is only a manner of speaking. However, my_union1 by itself does
not have a value; only its members have values.) On the other hand, if
you then type my_union1.float_member = 7.7;, the my_union
variable loses its integer value. It is crucial to remember that a
union variable can only have one type at the same time.
