Problem when typecasting a void * pointer used inside a structure to an int * pointer?

Struct data *d merely declares a pointer. You have not allocated this struct anywhere. You need to either malloc it or declare it just as struct data d on the stack or globally.

Struct data *d merely declares a pointer. You have not allocated this struct anywhere. You need to either malloc it or declare it just as struct data d on the stack or globally.

The former can be done like this: d = malloc(sizeof(struct data)); If you choose the latter, accessing be has to be written as d.b.

You are not allocating any memory for d. It likely points to an invalid memory area and so - segmentation fault. You can solve this like so: struct data *d = malloc(sizeof(*d)).

You are getting segmentation fault at the line d->b=&key; Note that you have not allocated any memory location to the structure variable d. So d contains some garbage value, and d->b it trying to use that garbage address to dereference the pointer and get the component b. Here is where you get the segfault.

Either statically allocate the struct variable, or use malloc to dynamically allocate it. Int main() { struct data *d; int *ptr; /* Here you are allocating memory to the * pointer variable, which will be used to * point to the structure type data */ d = malloc (sizeof (struct data)); int key=10000; /* Now you can dereference the pointer * and get any of the components of the * structure, because 'd' contains a valid * address. */ d->b=&key; ptr=(int *)d->b; printf("%d\n",*ptr); /* Good practice to free the memory location * you have allocated.

Not freeing will lead to * memory leak in larger applications. After you * free the memory location denoted by the address * stored in 'd', you will not be anymore access * the contents of it. */ free (d); /* d->b; or d->a; is no more possible at this point * as we have freed the memory pointed by 'd' */ } Or you can use: int main() { /* Not a pointer, statically allocated */ struct data d; int *ptr; int key=10000; d.

B=&key; ptr=(int *)d. B; printf("%d\n",*ptr); } So, it is not the typecasting of void * to int * that causes the segfault. Its the illegal memory reference of the pointer variable which you have used but not allocated/initialized.

The problem is that you didn't allocate memory for a d pointer: struct data *d;. This lines only creates a pointer, it doesn't alloc memory for it. Please try the following code: int main() { struct data *d = (struct data*)malloc(sizeof(struct data)); int *ptr; int key=10000; d->b=&key; ptr=(int *)d->b; printf("%d\n",*ptr); free(d); }.

4 Don't cast the return value of malloc. – cnicutar Jun 8 at 14:29.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.