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GO Classes DPP | GATE CS | C Programming | Structure Pointer Precedence

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6 6 votes

What will happen when the following code is compiled?

#include <stdio.h>

struct Node {
    int data;
};

int main() {
    struct Node n = {25};
    struct Node *p = &n;

    printf("%d", *p.data);

    return 0;
}
  1. $\texttt{25}$
     
  2. Address of $\texttt{data}$
     
  3. Compilation error
     
  4. Undefined behavior

2 Answers

1 1 vote

Here, $\texttt{p}$ is a pointer to a structure.

To access the member using a structure pointer, we should write:

$\texttt{p->data}$

or

$\texttt{(*p).data}$

But the code uses:

$\texttt{*p.data}$

The dot operator $\texttt{.}$ has higher precedence than the dereference operator $\texttt{*}$.

So, this expression is treated as:

$\texttt{*(p.data)}$

But $\texttt{p}$ is a pointer, not a structure variable.

So, $\texttt{p.data}$ is invalid.

Therefore, the code gives a compilation error.


Answer: C

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