Structures In C Programming

Structure is a user-defined data type

It is the collection of different data elements

struct keyword is used to define a structure

dot operator(.) is used for accessing members.

When a variable is associated with a structure, the compiler allocates the memory for each member. 

The size of structure is greater than or equal to the sum of sizes of its members.

Individual member can be accessed at a time.

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(->)

Member operator (.)
Any members of a structure can be accessed by(.) operator

Step 1:

Syntax:

struct[structure name]
{

Member definition;

Member definition;

..

Member definition

};

Step 2:

Example:

struct Employee

{

    char name[50]; //1byte memory

    int id;                //2 byte

    float salary;        //4byte   

} e1;

Note:

7 bytes memory is allocated because the compiler allocates the memory for each member.

Step 3:

Declaring structure:
struct Employee e1;

Step 4:

Initializing structure:
struct  Employee e1={"suryosnata",1,35000.45};

Step 5:

Accessing structure members :
e1.name

e1.id

e1.salary

Note:

You can initialize structure in two ways, they are

1^st way:

 struct  Employee e1;

 e1.id=1;

 strcpy(e1.name, "Suryosnata");

  e1.salary =35000.56; 

//When you prefer 1^st way then use header file like #include<string.h> for any string  variable.

2^nd way:

struct Employee e1={"suryosnata",1,35000.45};

Example 1(1^st  way):

#include <stdio.h>

#include<string.h>

#include<conio.h>

struct Employee

{

    char name[50];

    int id;

    float salary;

};

void main()

{

   struct Employee e1;

   e1.id=1;

   clrscr();

  strcpy(e1.name, "Suryosnata");

  e1.salary =35000.45;     

 printf(" Name is: %s \n", e1.name);

 printf(" Id is: %d \n", e1.id);

 printf(" Salary is: %f \n", e1.salary);

 getch();

}

Output:

Name is: suryosnata                                                                                                           

 Id is: 1                                                                                                                      

 Salary is: 35000.449219                                                                                                       

                          

Example 1 (2^nd way):

#include <stdio.h>

#include<conio.h>

struct Employee

{

    char name[50];

    int id;

    float salary;

};

void main()

{

struct Employee e1={"suryosnata",1,35000.45};

     

            printf(" Name is: %s \n", e1.name);

            printf(" Id is: %d \n", e1.id);

            printf(" Salary is: %f \n", e1.salary);

   getch();

}

Output:

Name is: suryosnata                                                                                                           

 Id is: 1                                                                                                                      

 Salary is: 35000.449219                                                                                                       

                          

Example 2:(Taking value from user)

#include <stdio.h>

#include<conio.h>

struct Employee

{

    char name[50];

    int id;

    float salary;

} e1;

void main()

{

    clrscr();

    printf("Enter  Employee information:\n");

    printf("Enter NAME: ");

    scanf("%s", e1.name);

    printf("Enter ID: ");

    scanf("%d", &e1.id);

    printf("Enter SALARY: ");

    scanf("%f", &e1.salary);

    printf("Employee Information:\n");

    printf("Name: %s\n",e1.name);

    printf("Id: %d\n",e1.id);

    printf("Salary: %f\n", e1.salary);

   getch();

}
Output:

Enter  Employee information:                                                                                                   

Enter NAME: surya                                                                                                              

Enter ID: 123                                                                                                                  

Enter SALARY: 35000                                                                                                            

Employee Information:                                                                                                          

Name: surya

Id: 123                                                                                                                        

Salary: 35000.000000 

Structure pointer operator (->)

If we have a pointer to structure then members are accessed using arrows (->) operator.

Step 1:

Syntax:

struct[structure name]

{

Member definition;

Member definition;

..

Member definition

};

Step 2:

Example:

struct Employee

{

    char name[50]; //1byte memory

    int id;                //2 byte

    float salary;        //4byte   

} e1;

Note:

7 bytes memory is allocated because the compiler allocates the memory for each member.

Step 3:

Initializing structure 

struct Employee e1={"suryosnata",1,35000.45};

Step 4:

Declaring structure using pointer variable:

struct student *pt;

pt=&e1;

Step 5:

Accessing structure members using pointer variable:

pt->name
pt->id

pt->salary

Example 1:

#include <stdio.h>

#include<conio.h>

struct Employee

{

    char name[50];

    int id;

    float salary;

};

 void main()

{

 struct Employee e1={"suryosnata",1,35000.45};

 struct Employee *pt;

  pt=&e1;

  printf(" Name is: %s \n",pt->name);

  printf(" Id is: %d \n",pt->id);

  printf(" Salary is: %f \n",pt->salary);

   getch();

}

Output:

Name is: suryosnata                                                                                                           

 Id is: 1                                                                                                                      

 Salary is: 35000.449219 

         Example 2:

     #include <stdio.h>

     #include<conio.h>

       struct  Demo

{

   int a, b;

};

void main()

{

  struct Demo p1 = {143, 142};

   struct Demo *p2 = &p1;

   printf("%d %d", p2->a, p2->b);

  getch();

}

Output:

143  142