![Structure declarations
4
To define a structure, you must use the struct statement. The struct statement
defines a new data type, with more than one member. The format of the struct
statement is as follows −
struct [structure tag] {
member definition;
member definition;
...
member definition;
} [one or more structure variables];
struct person
{
char name[50];
int cit_no;
float salary;
};
We can create the structure for a
person as mentioned above as:](https://image.slidesharecdn.com/mine-170227205159/85/C-programing-Structure-4-320.jpg)
![Structure variable declaration
5
When a structure is defined, it creates a user-defined type
but, no storage is allocated. For the above structure of person,
variable can be declared as:
struct person
{
char name[50];
int cit_no;
float salary;
};
Inside main function:
struct person p1, p2, p[20];
Another way of creating sturcture variable
is: struct person
{
char name[50];
int cit_no;
float salary;
}p1 ,p2 ,p[20];](https://image.slidesharecdn.com/mine-170227205159/85/C-programing-Structure-5-320.jpg)
![Example using function and pointer:
10
#include <stdio.h>
#include <string.h>
struct Books {
char title[50];
char author[50];
char subject[100];
int book_id;
};
/* function declaration */
void printBook( struct Books *book );
int main( ) {
struct Books Book1; /* Declare Book1 of type Book */
struct Books Book2; /* Declare Book2 of type Book */
/* book 1 specification */
strcpy( Book1.title, "C Programming");
strcpy( Book1.author, "Nuha Ali");
strcpy( Book1.subject, "C Programming Tutorial");
Book1.book_id = 6495407;
/* book 2 specification */
strcpy( Book2.title, "Telecom Billing");
strcpy( Book2.author, "Zara Ali");
strcpy( Book2.subject, "Telecom Billing Tutorial");
Book2.book_id = 6495700;](https://image.slidesharecdn.com/mine-170227205159/85/C-programing-Structure-10-320.jpg)
C programing -Structure
- 2. Contents: Introduction Syntax and formation Variables and member accessing Nesting of structures Use of function and pointer in structure 2
- 3. Intro: Structure is another user defined data type like array available in C , that allows to combine data items of different kinds of data types, whereas arrays allow only of same data type . Structures are used to represent a record. Suppose you want to keep track of your books in a library. You might want to track the following attributes about each book − Title − Author − Subject − Book ID 3 All these data can be saved under a single name in STRUCTURE
- 4. Structure declarations 4 To define a structure, you must use the struct statement. The struct statement defines a new data type, with more than one member. The format of the struct statement is as follows − struct [structure tag] { member definition; member definition; ... member definition; } [one or more structure variables]; struct person { char name[50]; int cit_no; float salary; }; We can create the structure for a person as mentioned above as:
- 5. Structure variable declaration 5 When a structure is defined, it creates a user-defined type but, no storage is allocated. For the above structure of person, variable can be declared as: struct person { char name[50]; int cit_no; float salary; }; Inside main function: struct person p1, p2, p[20]; Another way of creating sturcture variable is: struct person { char name[50]; int cit_no; float salary; }p1 ,p2 ,p[20];
- 6. Member access 6 Accessing members of a structure There are two types of operators used for accessing members of a structure. 1. Member operator(.) 2. Structure pointer operator(->) Any member of a structure can be accessed as: structure_variable_name.member_name Suppose, we want to access salary for variable p2. Then, it can be accessed as: p2.salary
- 7. Nested Structures 7 Structures can be nested within other structures in C programming. struct complex { int imag_value; float real_value; }; struct number{ struct complex c1; int real; }n1,n2; Suppose you want to access imag_value for n2 structure variable then, structure member n1.c1.imag_value is used.
- 8. Sample program CS 3090: Safety Critical Programming in C 8
- 9. Pointers to Structure : 9 We can define pointers to structures in the same way as we define pointer to any other variable − struct Books *struct_pointer; Now, we can store the address of a structure variable in the above defined pointer variable. To find the address of a structure variable, place the '&'; operator before the structure's name as follows − struct_pointer = &Book1; To access the members of a structure using a pointer to that structure, you must use the -> operator as follows − struct_pointer->title;
- 10. Example using function and pointer: 10 #include <stdio.h> #include <string.h> struct Books { char title[50]; char author[50]; char subject[100]; int book_id; }; /* function declaration */ void printBook( struct Books *book ); int main( ) { struct Books Book1; /* Declare Book1 of type Book */ struct Books Book2; /* Declare Book2 of type Book */ /* book 1 specification */ strcpy( Book1.title, "C Programming"); strcpy( Book1.author, "Nuha Ali"); strcpy( Book1.subject, "C Programming Tutorial"); Book1.book_id = 6495407; /* book 2 specification */ strcpy( Book2.title, "Telecom Billing"); strcpy( Book2.author, "Zara Ali"); strcpy( Book2.subject, "Telecom Billing Tutorial"); Book2.book_id = 6495700;
- 11. Example using function and pointer: 11 /* print Book1 info by passing address of Book1 */ printBook( &Book1 ); /* print Book2 info by passing address of Book2 */ printBook( &Book2 ); return 0; } void printBook( struct Books *book ) { printf( "Book title : %sn", book->title); printf( "Book author : %sn", book->author); printf( "Book subject : %sn", book->subject); printf( "Book book_id : %dn", book->book_id); } Book title : C Programming Book author : Nuha Ali Book subject : C Programming Tutorial Book book_id : 6495407 Book title : Telecom Billing Book author : Zara Ali Book subject : Telecom Billing Tutorial Book book_id : 6495700 OUTPUT
- 12. 12