C Language Programming - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 223

unsigned int date;

unsigned char rev;

} card;
where the variable card is of type catalog_tag .
A structure definition that is not followed by a list of variables reserves no storage; it merely
describes a template or the shape of a structure. If the declaration is tagged (i.e., has a name),
however, the tag can be used later in definitions of instances of the structure. For example, sup-
pose we have the following structure declaration:
struct point {

int x;

int y;

};
We can then define a variable pt of type point as follows:
struct point pt;
A member of a particular structure is referred to in an expression by a construction of the form
structure-name.member or structure-pointer → member
The structure member operator . connects the structure name and the member name. As
an example, the square of the distance of a point to the origin can be computed as follows:
long integer sq_distance;
. . .
sq_distance 5 pt.x * pt.x 1 pt.y * pt.y;
Structures can be nested. One representation of a circle consists of the center and radius, as
shown in Figure 5.1.

y

Radius

Center

x

Figure 5.1 ■ A circle

This circle can be defined by
struct circle {

struct point center;

unsigned int radius;

};