Question

Can math operations be performed on a void pointer?

Answer 1

According to c standard arithmetic operation on void pointers is illegal that means the C standard doesn’t allow pointer arithmetic with void pointers. However, In GNU C, addition and subtraction operations are supported on void pointers to assuming the size of the void is 1.

Let see an example

#include<stdio.h>

int main()

{

int aiData[3] = {100, 200,300};

void *pvData = &aiData[1]; //address of 200

pvData += sizeof(int);

printf("%d", *(int *)pvData);

return 0;

}

Output: 300 or compiler error.

Explanation: When we compile the code then some compiler throw the compiler error but some compiler compiled the code and print 300 as output to assume the size of the void 1.

Note: Don’t perform the arithmetic operation on the void pointer. As per the C standard sizeof is not applicable on void but in GNU C we can calculate the size of the void and sizeof operator return 1.