Structures

Arrays allow to define type of variables that can hold several data items of the same kind. Similarly structure is another user defined data type available in C that allows to combine data items of different kinds.

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

Defining a Structure

struct <name> 
{ 
	member definition; 
	member definition; 
	... 
	member definition; 
} [one or more structure variables]; 

struct Books 
{ 	char title[50]; 
	char author[50]; 
	char subject[100]; 
	int book_id; 
} book; 

Structure Variables

struct Person 
{ 
	// code 
}; 

int main() 
{ 
	struct Person person1, person2, p[20]; 
	return 0; 
} 

Another way to define Structure Variables


struct Person 
{ 
	// code 
} person1, person2, p[20]; 

Using typedef

struct Distance
{ 
	int feet; 
	float inch; 
}; 

int main() 
{ 
	struct Distance d1, d2; 
} 

{typedef struct Distance 

	int feet;
  	float inch;
}distances;

int main() 
{
	distances d1, d2;
}

Example

#include <stdio.h>
#include <string.h>

struct Person {
  char name[50];
  int citNo;
  float salary;
} person1;

int main() {

strcpy(person1.name, "George Orwell");

person1.citNo = 1984;
person1. salary = 2500;

printf("Name: %s\n", person1.name);
printf("Citizenship No.: %d\n", person1.citNo);
printf("Salary: %.2f", person1.salary);

  return 0;
}

Nested Structure

struct complex {
  int imag;
  float real;
};

struct number {
  struct complex comp;
  int integers;
} num1, num2;