pointer paradox

[sbasak]

why this code gives error

main()
{
int *x;
*x = 5;
printf("%d",*x);
}


it works with some compiler but not with others. If I use malloc, then it works fine everywhere. Can you tell why?

[jim mcnamara]

Yes.

*x is supposed to point to some place in memory. At that place in memory is a variable of type int. Only you do not create any variable in memory for x to aim at.

Just declaring like that has x referring to nothing. malloc() gives it something to refer to.

int main()
   int y;
   int *x;
   x = &y;
   *x = 5;
  printf("%d  %d\n",*x,y);
  return 0;
}