Page 103 - Programming Microcontrollers in C

88 Chapter 2 Advanced C Topics

a floating-point number. The structure declaration must be followed
by a semicolon. This combination of variables is created every time
a structure of the type person is declared. The name person follow­
ing the struct declaration is called the structure tag or merely the
tag. Tags are optional. If a tag is used, it may be used to declare other
structures of the same type by
struct person ap,bp,cp;

Here ap,bp, and cp are structures of the type person. A single
instance of a structure can be declared by

struct {....} a;
In this case a is a structure with the elements defined between the
braces. The elements that make up a structure are called its mem­
bers. Members of a structure can be accessed by appending a period
followed by the member name to the structure name. For example,
the name of the person represented by ap is accessed by

ap.name
and that person’s salary is

ap.salary
A pointer to a structure can be used. The pointer pperson is created by

struct person *pperson;
If a pointer to a structure is used, members of the structure can be
accessed by the use of a special operator ->. This operator is created
by use of the minus sign (-) followed by the right angle bracket
character (>). The height of a person identified by the pointer
pperson is accessed by
pperson->height

Arrays of structures are used, and when dealing with pointers to ar­
rays of structures, to increment the pointer will move the pointer to
the next structure. If a program has

struct person people[20], *pp;
and pp is made to point at people[0] by

pp=people