Void Pointer in C

Void Pointer

The void pointer is declared as void * and can be used to pass pointers to functions that do not need to know the data type they are handling.

It is also known as a "generic pointer", and can hold the address of any type of data, but it does not know the type of the data it is pointing to. However, before dereferencing a void pointer, it must be cast to the correct data type.

Void Pointer - Examples

Example 1

#include <stdio.h>

int main()
{
    int num = 10;
    char c = 'a';
    void *ptr;

    // Assign the address of an int to the void pointer
    ptr = &num;

    // Cast the void pointer to an int pointer and dereference it
    printf("The value of num is %d\n", *(int *)ptr);

    // Assign the address of a char to the void pointer
    ptr = &c;

    // Cast the void pointer to a char pointer and dereference it
    printf("The value of c is %c\n", *(char *)ptr);

    return 0;
}

Output:

Explanation

• A void pointer is used to store the address of an integer and a character.

• The void pointer is then cast to the appropriate pointer type (int* and char*) before dereferencing it to obtain the value of the data being pointed to.

Example 2

#include <stdio.h>

void print_value(void *ptr, char type)
{
    switch (type)
    {
        case 'i':
            printf("%d\n", *(int *)ptr);
            break;
        case 'f':
            printf("%f\n", *(float *)ptr);
            break;
        case 'c':
            printf("%c\n", *(char *)ptr);
            break;
        default:
            printf("Invalid type\n");
            break;
    }
}

int main()
{
    int i = 10;
    float f = 3.14;
    char c = 'a';

    // Call the print function with different types of data
    print_value(&i, 'i');
    print_value(&f, 'f');
    print_value(&c, 'c');

    return 0;
}

Output:

Example

• The print_value() function takes a void pointer and a character representing the type of data being pointed to.
• The function uses a switch statement to cast the void pointer to the appropriate type (int*, float*, or char*) and then prints the value of the data being pointed to.
• The main function calls the print_value() function with different types of data to demonstrate its ability to print values of different types using a single function.