Structures in C

Posted on November 18, 2023 by Vishesh Namdev

Python C C++ Java

Structure in C is like a custom data container that lets you bundle different types of variables together under one label. It helps in organizing and managing related information in your program. Each piece of data inside the structure has its own name and type, making it easier to work with and understand complex data relationships.

Syntax of Structure

struct structure_name {
    data_type member1;
    data_type member2;
    // ... more members if needed
;

Declaring and Accessing Structures

You can declare variables of a structure type in the same way you declare variables of basic data types.

struct Student stud1; // Declaration of a structure variable

// Accessing and assigning values
strcpy(stud1.name, "Alice");
stud1.age = 20;
stud1.gpa = 3.8;

// Accessing structure members is done using the dot (.) operator.
printf("Student Name: %s\n", stud1.name);
printf("Age: %d\n", stud1.age);
printf("GPA: %.2f\n", stud1.gpa);

Why use Structures

1. Grouping Related Data: Allow you to group together variables of different data types under a single name. This is useful when dealing with entities that have multiple attributes. For example, a Person structure might include fields for name, age, and address.

2. Memory Allocation and Alignment: Structures help in efficient memory allocation and alignment. The members of a structure are stored in contiguous memory locations, making it easier to manage and access the data.

3. Enhanced Readability: Using structures makes the code more readable and self-explanatory. Instead of dealing with individual variables scattered throughout the code, you can encapsulate related variables within a structure, making the code easier to understand.

4. Passing and Returning Complex Data:Structures enable you to pass and return complex data structures to and from functions. This is particularly useful when you want to work with entities that have multiple attributes without having to pass each attribute separately.

5. Code Modularity:Structures contribute to code modularity by encapsulating related data and functionality within a single unit. This makes it easier to maintain and update code since changes to the structure can be isolated.

Example of Structure

#include <stdio.h>Copy Code
// Define a Point structure with x and y coordinates
struct Point {
    int x;
    int y;
};
int main() {
    // Declare a variable of type Point
    struct Point p1;

    // Assign values to the members
    p1.x = 10;
    p1.y = 5;

    // Display the coordinates
    printf("Point coordinates: (%d, %d)\n", p1.x, p1.y);

    return 0;
}

Output

Point coordinates: (10, 5)

Nesting structures in C

Nesting structures in C involves defining a structure within another structure. This allows you to represent hierarchical relationships or group related data in a more organized manner.

Example of Nesting Structures

#include <stdio.h>Copy Code
// Define an Address structure
struct Address {
    char street[50];
    char city[30];
    int zip_code;
;
// Define a Person structure that includes an Address structure
struct Person {
    char name[50];
    int age;
    struct Address address; // Nesting the Address structure
;
int main() {
    // Declare a variable of type Person
    struct Person person1;

    // Access and assign values to the members
    strcpy(person1.name, "John Doe");
    person1.age = 25;

    // Access and assign values to the nested Address structure
    strcpy(person1.address.street, "123 Main St");
    strcpy(person1.address.city, "Anytown");
    person1.address.zip_code = 12345;

    // Display the information
    printf("Person's name: %s\n", person1.name);
    printf("Person's age: %d\n", person1.age);
    printf("Person's address:\n");
    printf("Street: %s\n ",person1.address.street);
    printf("City: %s\n", person1.address.city );
    printf("ZIP Code: %d\n", person1.address.zip_code);

    return 0;
}

Output

Person's name: John Doe
Person's age: 25
Person's address:
Street: 123 Main St
City: Anytown
ZIP Code: 12345

In this example, structures are used to represent a person's information and address. The Person structure includes a nested Address structure. A variable, person1, is declared and initialized, and values are assigned to both structures' members. The program then displays the person's details, demonstrating how nesting structures enhances the modeling of real-world relationships, especially in complex data structures.