struct

Keyword

Groups variables into a single record.

The syntax for defining records is:

struct [struct-type-name]
  {
    [type variable-names] ;
    ...
  } [structure-variables] ;

A struct, like an union, groups variables into a single record. The struct-type-name is an optional tag name that refers to the structure type. The structure-variables are the data definitions, and are also optional. Though both are optional, one of the two must appear.

Elements in the record are defined by naming a type, followed by variable-names separated by commas. Different variable types can be separated by a semicolon. For example,

struct my_struct
  {
    char name[80], phone_number[80];
    int age, height;
  } my_friend;

declares a record variable my_friend containing two strings (name and phone_number) and two integers (age and height). To declare additional variables of the same type, you use the keyword struct followed by the struct-type-name, followed by the variable names. For example,

struct my_struct my_friends[100];

declares an array named my_friends which components are records. In fact, 'struct my_struct' becomes a new type which is equal in rights with any built-in type.

To access elements in a structure, you use a record selector ('.'). For example,

strcpy (my_friend.name, "Mr. Wizard");

A bit field is an element of a structure that is defined in terms of bits. Using a special type of struct definition, you can declare a structure element that can range from 1 to 16 bits in length. For example,

struct bit_field
  {
    int bit_1 : 1;
    int bits_2_to_5 : 4;
    int bit_6 : 1;
    int bits_7_to_16 : 10;
  } bit_var;