This document provides a comprehensive guide to structures and unions in C programming. It covers the key concepts of structure declaration, initialization, and accessing members, along with the differences between structures and unions. You’ll learn how to use unions to save memory, and when to ...
Structures and Unions in C
A structure and a union are both user-defined data types in C, used for grouping
different types of variables together under a single name. They differ in how they
manage memory, which affects how the data is stored and accessed.
1. Structures in C
A structure is a collection of variables of different data types grouped together
under one name. Each variable within the structure is known as a member, and
members can be of different data types, including arrays, pointers, and other
structures.
Declaration and Initialization of a Structure
To define a structure, you use the struct keyword. Here’s how you can define and
initialize a structure in C:
#include <stdio.h>
struct Person {
char name[50];
int age;
float height;
};
int main() {
// Declaring and initializing a structure variable
struct Person person1 = {"Alice", 25, 5.6};
struct Person is the structure definition.
person1 is a variable of type struct Person.
The members name, age, and height are accessed using the dot operator
(.).
Accessing Structure Members
You can access the members of a structure using the dot operator (.) if you have
an instance of the structure. For example, person1.name accesses the name
member of the person1 instance.
To access members of a structure through a pointer, you would use the arrow
operator (->).
Example using a pointer to a structure:
#include <stdio.h>
struct Person {
char name[50];
int age;
float height;
};
int main() {
struct Person person1 = {"Bob", 30, 5.9};
struct Person *ptr = &person1;
// Accessing structure members via pointer
printf("Name: %s\n", ptr->name);
printf("Age: %d\n", ptr->age);
printf("Height: %.2f\n", ptr->height);
return 0;
}
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