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The ‘void’ Keyword in C Programming

   January 1, 2024
C Programming @ Freshers.in

In the realm of C programming, the ‘void’ keyword is a versatile and powerful tool that plays a pivotal role in managing functions, pointers, and data structures. This comprehensive article aims to elucidate the ‘void’ keyword, explaining its purpose, usage, and providing real-world examples with outputs. By the end, you’ll have a deep understanding of how ‘void’ empowers you to work with various aspects of C programming effectively.

The Purpose of the ‘void’ Keyword

The ‘void’ keyword in C serves two main purposes:

  1. It is used as a return type for functions that do not return any value (void functions).
  2. It is employed as a pointer type, indicating that a pointer can point to an object of any data type.

Usage of the ‘void’ Keyword

  1. Void Functions: To declare a function that doesn’t return any value, you specify ‘void’ as the return type. These functions are typically used for performing tasks or operations without returning a result.
  2. Void Pointers: A ‘void’ pointer (void*) is a pointer that can be used to point to objects of any data type. It provides flexibility in handling different data types dynamically.

Example 1: Using ‘void’ as a Return Type

Let’s create a void function that prints a greeting message without returning any value:

#include <stdio.h>
void greet() {
    printf("Hello, C Programmer!\n");
}
int main() {
    greet();
    return 0;
}

In this example, the ‘greet’ function is declared with a ‘void’ return type, indicating that it doesn’t return any value.

Output:

Hello, C Programmer!

Example 2: Using ‘void’ Pointers

Void pointers are particularly useful when you need to allocate memory dynamically and work with different data types. Let’s create a program that demonstrates the use of a ‘void’ pointer to dynamically allocate memory for an integer:

#include <stdio.h>
#include <stdlib.h>
int main() {
    int* intPtr;
    void* voidPtr;
    int num = 42;
    intPtr = &num;
    voidPtr = malloc(sizeof(int)); // Allocate memory for an integer
    if (voidPtr != NULL) {
        *((int*)voidPtr) = 99; // Store an integer in the allocated memory
        printf("Value stored in voidPtr: %d\n", *((int*)voidPtr));
        free(voidPtr); // Deallocate memory
    }
    return 0;
}

In this example, we allocate memory for an integer using a ‘void’ pointer and then access and modify the value stored in that memory location.

Output:

Value stored in voidPtr: 99
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