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GO Classes DPP | GATE CS | C Programming | Invalid Pointer Addition

190 views
5 5 votes

Consider the following declarations:

#include <stdio.h>

int main() {
    int a[4] = {6, 4, 1, 2};
    int b[8] = {9, 8, 11, 10, 5, 7, 0, 3};

    int *p = &a[1];
    int *q = b;

    printf("%p", p + q);

    return 0;
}

What will happen?

  1. It prints the sum of two addresses
     
  2. It prints the address of $\texttt{a[1] + b[0]}$
     
  3. Compilation error
     
  4. Undefined behavior after successful compilation

1 Answer

3 3 votes

In C, adding two pointers is not allowed.

This expression is invalid:

$\texttt{p + q}$

Pointer arithmetic allows adding an integer to a pointer, like:

$\texttt{p + 1}$

But adding one pointer to another pointer is not valid.

So,

$\texttt{p + q}$

will cause a compilation error.

Therefore, the correct answer is $\texttt{Compilation error}$.

Answer: C

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