Structures and Unions in C

Structures and unions are user-defined data types in C that allow storing multiple related variables under a single name. They help organize complex data efficiently.

Structures in C

A structure is a collection of different data types grouped together under one name.

Declaring a Structure

A structure is defined using the struct keyword.

struct Student {
    char name[50];
    int age;
    float marks;
};

Accessing Structure Members

Structure members are accessed using the dot (.) operator.

struct Student s1;
s1.age = 20;
s1.marks = 85.5;

Initializing Structures

Structures can be initialized at the time of declaration.

struct Student s1 = {"John Doe", 20, 85.5};

Example Program

#include <stdio.h>

struct Student {
    char name[50];
    int age;
    float marks;
};

int main() {
    struct Student s1 = {"Alice", 22, 90.5};
    printf("Name: %s\n", s1.name);
    printf("Age: %d\n", s1.age);
    printf("Marks: %.2f\n", s1.marks);
    return 0;
}

Unions in C

A union is similar to a structure but uses shared memory, meaning only one member can store a value at a time.

Declaring a Union

A union is defined using the union keyword.

union Data {
    int i;
    float f;
    char str[20];
};

Accessing Union Members

Since all members share the same memory, changing one affects others.

union Data d;
d.i = 10;
printf("%d", d.i);

Example Program

#include <stdio.h>

union Data {
    int i;
    float f;
    char str[20];
};

int main() {
    union Data d;
    d.i = 10;
    printf("Integer: %d\n", d.i);
    d.f = 20.5;
    printf("Float: %.2f\n", d.f);
    return 0;
}

Difference Between Structure and Union

If you have any questions, feel free to ask. Thank you for reading!