What is the meaning of segmentation fault? What causes the fault to arise in mai

Question

What is the meaning of segmentation fault? What causes the fault to arise in main() when executing a.out? Add two additional #ifdef conditional debug printf() calls in the function changeval() to pinpoint where the seg fault occurs.

#include <stdio.h>

#define MYDEBUG

int main()

{

int x;

void changeval(int *);

x = 6;

printf("%d ",x);

#ifdef MYDEBUG

printf("ok 1 ");

#endif

changeval(&x);

#ifdef MYDEBUG

printf("ok 2 ");

#endif

printf("%d ",x);

#ifdef MYDEBUG

printf("ok 3 ");

#endif

changeval(x);

#ifdef MYDEBUG

printf("ok 4 ");

#endif

printf("%d ",x);

}

void changeval(int *a)

{

*a = 3;

}

Explanation / Answer

Hi

I have fixed the issue and highlighted the code changes below

A segmentation fault occurs when a program attempts to access a memory location that it is not allowed to access, or attempts to access a memory location in a way that is not allowed

#include <stdio.h>

#define MYDEBUG

int main()

{

int x;

void changeval(int *);

x = 6;

printf("%d ",x);

#ifdef MYDEBUG

printf("ok 1 ");

#endif

changeval(&x);

#ifdef MYDEBUG

printf("ok 2 ");

#endif

printf("%d ",x);

#ifdef MYDEBUG

printf("ok 3 ");

#endif

changeval(&x);

#ifdef MYDEBUG

printf("ok 4 ");

#endif

printf("%d ",x);

}

void changeval(int *a)

{

*a = 3;

}

Output:

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