Dereferencing Pointers

Consider

      #include <stdio.h>

      int main ()
      {
        int *p;
        int j = 4;

        p = &j;
        printf ("%d\n", *p);

        *p = 5;
        printf ("%d %d\n", *p, j);

        if (p != 0)
        { printf ("Pointer p points at %d\n", *p);
        }

        return 0;

      }

• *p dereferences pointer to access object pointed at

• *p can be used on either side of assignment operator

• if p is equal to 0, then pointer is pointing at nothing and is called a null pointer

• dereferencing a null pointer causes a core dump :-(