C Nested Structure

You can define nested structures, which are structures that are members of another structure. This allows you to create hierarchical and complex data structures where a structure can contain one or more structures as its members. Nested structures are useful for organizing and representing data that has a hierarchical or composite nature.

Here’s how you can define and use nested structures in C:

#include <stdio.h>

// Define the inner structure
struct Address {
    char street[50];
    char city[50];
    char state[20];
    char postal_code[10];
};

// Define the outer structure containing the inner structure
struct Person {
    char name[50];
    int age;
    struct Address address; // Nested structure as a member
};

int main() {
    // Declare a variable of type 'struct Person'
    struct Person person1;

    // Assign values to the members of the outer and inner structures
    strcpy(person1.name, "John");
    person1.age = 30;
    strcpy(person1.address.street, "123 Main St");
    strcpy(person1.address.city, "Anytown");
    strcpy(person1.address.state, "CA");
    strcpy(person1.address.postal_code, "12345");

    // Access and print the members of the structures
    printf("Name: %s\n", person1.name);
    printf("Age: %d\n", person1.age);
    printf("Address:\n");
    printf("  Street: %s\n", person1.address.street);
    printf("  City: %s\n", person1.address.city);
    printf("  State: %s\n", person1.address.state);
    printf("  Postal Code: %s\n", person1.address.postal_code);

    return 0;
}

In this example, we define two structures: struct Address and struct Person. struct Address represents an address with its own members (street, city, state, postal code), and struct Person represents a person with its own members (name, age) and includes an instance of struct Address as a member.

You can access the members of the nested structure using the dot notation, as demonstrated in the main() function.

Nested structures are commonly used when you need to model real-world entities that have a hierarchical structure. They help in organizing and encapsulating data efficiently, making the code more readable and maintainable.