Crashing when trying to modify constant variable through a pointer

Question

I got a program crash when I am trying to modify constant variable through a pointer.

#include <stdio.h>

static const int x = 5;

void changeX(int *x)
{
    (*x) = 20;
    printf("%d", (*x));
}

int main(void)
{
    printf("Jelele");
    changeX((int *)&x);
    return 0;
}

I know it isn't a good practice and there is no need to make such that ... I am just testing something ...

My question is:

Why program crashes ?!

Rather we were expecting a question, `Why program is not crashing?`. You're just lucky. :-) — Sourav Ghosh, Jan 17 '15 at 09:53

score 2 · Answer 1 · edited May 23 '17 at 12:14

2

static const int x = 5;

This is a constant variable stored in read-only location so when you try to write to this location then you see a crash.

Like

(*x) = 20; /* This is UB */

Check the below link:

Where are constant variables stored in C?

edited May 23 '17 at 12:14

Community

1
1

answered Jan 17 '15 at 09:43

Gopi

19,784
4
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score 1 · Accepted Answer · answered Jan 17 '15 at 09:44

1

You could change where the pointer x points to, but as the integer x is constant, its value cannot obviously be changed by definition.

answered Jan 17 '15 at 09:44

Roope Hakulinen

7,326
4
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Crashing when trying to modify constant variable through a pointer

2 Answers2