Pointer to structures

Posted on June 20, 2020

C program to show the usage of pointer to structures.

Program 

#include<stdio.h>
#include<conio.h>

struct person
{
    char name[20];
    int age;
    float weight;
};

void main()
{
 	struct person p1;
    struct person *ptr;

    ptr = &p1;

    printf("Enter name\t:");
    scanf("%s",ptr->name);
    printf("Enter age\t:");
    scanf("%d",&ptr->age);
    printf("Enter weight\t:");
    scanf("%f",&ptr->weight);

    printf("\n\nEntered data is");
    printf("\nName\t:%s",ptr->name);
    printf("\nAge\t:%d",ptr->age);
    printf("\nWeight\t:%f",ptr->weight);

    getch();  
}

Output 

Enter name      :Aman
Enter age       :30
Enter weight    :93.8


Entered data is
Name    :Aman
Age     :30
Weight  :93.800000

Explanation

In the above program, a structure 'person' is defined and a variable 'p1' of struct person type is declared. A struct pointer 'ptr' is also declared. The starting address of 'p1' is stored in the 'ptr' pointer using
ptr = &p1;

Now, you can access the members of 'p1' using the 'ptr' pointer. To access members of structure using the structure variable, we used the dot (.) operator. But when we have a pointer of structure type, we use arrow (->) to access structure members.
ptr->age
ptr->weight

Note that,
ptr->age is equivalent to (*ptr).age
>ptr->weight is equivalent to (*ptr).weight
Program for the same is shown in "Method 2" tab.

Program 

#include<stdio.h>
#include<conio.h>

struct person
{
    char name[20];
    int age;
    float weight;
};

void main()
{
    struct person p1;
    struct person *ptr;

    ptr = &p1;

    printf("Enter name\t:");
    scanf("%s",(*ptr).name);
    printf("Enter age\t:");
    scanf("%d",&(*ptr).age);
    printf("Enter weight\t:");
    scanf("%f",&(*ptr).weight);

    printf("\n\nEntered data is");
    printf("\nName\t:%s",(*ptr).name);
    printf("\nAge\t:%d",(*ptr).age);
    printf("\nWeight\t:%f",(*ptr).weight);

    getch();
}

Output 

Enter name      :Nisha
Enter age       :32
Enter weight    :75.3


Entered data is
Name    :Nisha
Age     :32
Weight  :75.300000