Accessing structure members in C involves using the dot (.) operator to refer to individual members of a structure variable. This allows you to read or modify the values of the structure members.

Defining a Structure

To access members of a structure, you must first define a structure and then declare a variable of that structure type:

struct Person {
    char name[50];
    int age;
    float height;
};

In this example, Person is a structure type containing three members: name, age, and height.

Declaring a Structure Variable

After defining the structure, you can declare a variable of that type:

struct Person person1;

Accessing Members

To access or modify the members of the structure, use the dot operator (.). The dot operator is used between the structure variable and the member name:

// Assigning values to the members
strcpy(person1.name, "Alice");
person1.age = 25;
person1.height = 5.7;

// Accessing and printing values of the members
printf("Name: %s\n", person1.name);    // Outputs: Name: Alice
printf("Age: %d\n", person1.age);      // Outputs: Age: 25
printf("Height: %.1f\n", person1.height); // Outputs: Height: 5.7

In this example:

• person1.name refers to the name member of the person1 structure.
• person1.age and person1.height access the age and height members, respectively.

Example Program

Here's a full example of defining, initializing, and accessing structure members:

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

struct Person {
    char name[50];
    int age;
    float height;
};

int main() {
    struct Person person1;

    // Assigning values to the structure members
    strcpy(person1.name, "Bob");
    person1.age = 30;
    person1.height = 6.1;

    // Accessing and printing structure members
    printf("Name: %s\n", person1.name);
    printf("Age: %d\n", person1.age);
    printf("Height: %.1f\n", person1.height);

    return 0;
}

Key Points to Remember

1. Dot Operator (.): Used to access individual members of a structure.

   • Syntax: structure_variable.member_name.
   • Example: person1.age = 25;

2. Assignment and Access:

   • You can assign values to structure members using the dot operator.
   • You can access the values of members the same way.

3. String Members:

   • For character arrays (strings), use functions like strcpy() to assign values since direct assignment (=) doesn’t work with arrays.

Example with Multiple Structure Variables

You can have multiple variables of the same structure type and access their members independently:

struct Person person1, person2;

strcpy(person1.name, "Alice");
person1.age = 25;
person1.height = 5.7;

strcpy(person2.name, "John");
person2.age = 28;
person2.height = 6.0;

printf("Person 1: %s, Age: %d, Height: %.1f\n", person1.name, person1.age, person1.height);
printf("Person 2: %s, Age: %d, Height: %.1f\n", person2.name, person2.age, person2.height);

Accessing Members via Pointers

If you have a pointer to a structure, you access its members using the arrow operator (->):

struct Person *ptr = &person1;
ptr->age = 26;  // Equivalent to (*ptr).age = 26
printf("Age: %d\n", ptr->age);

Summary

• Use the dot (.) operator to access members of a structure variable.
• Accessing members involves specifying the structure variable, followed by a dot, and then the member name.
• Pointers to structures use the arrow operator (->) to access members.

Accessing structure members is straightforward, and understanding it is crucial for working with user-defined data types in C.