# include <stdio.h>

int main ( )
{
  int a[3] = { 10, 20, 30 };
  int b[3] = { 40, 50, 60 };
  int c[3] = { 70, 80, 90 };
  int i;
  int value;
  int *vp;
//
//  The name of an array is a pointer.
//  If we want VP to point to A, we can simply use an "=" statement.
//
  vp = a;
  printf ( "  The value of A, which is a pointer, is %p\n", a );
  printf ( "  The value of VP, which is a pointer currently pointing to A, is %p\n", vp );

  printf ( "\n" );
  printf ( "  The first entry in A is A[0] = %i\n", a[0] );
  printf ( "  The third entry in A is A[2] = %i\n", a[2] );
  printf ( "\n" );
  printf ( "  The first entry in A is also *VP = %i\n", *vp );
  printf ( "  The third entry in A is also *(VP+2) = %i\n", *(vp+2) );
  printf ( "\n" );
  printf ( "  We are not allowed to change A, it always points to the array A.\n" );
  printf ( "  But we CAN change VP.\n" );
  printf ( "\n" );
  vp = vp + 1;
  printf ( "  After \"vp=vp+1\", we have *VP = %i\n", *vp );
  vp = vp + 1;
  printf ( "  After \"vp=vp+1\", we have *VP = %i\n", *vp );
  printf ( "\n" );
  printf ( "  Now, move VP to point to the B array.\n" );
  vp = b;
  printf ( "  After \"vp = b\", we have *VP = %i\n", *vp );
  printf ( "  Now use VP to change and print entries in B\n" );
  *vp = *vp + 1;
  printf ( "  After \"*vp = *vp + 1\", we have *VP = %i\n", *vp );
  printf ( "  If we add 1 to vp, we move to the next entry in B:\n" );
  vp = vp + 1;
  printf ( "  After \"vp=vp+1\", we have *VP = %i\n", *vp );
  printf ( "\n" );
  printf ( "  To sum the elements of C, we can use a loop that increments vp\n" );
  value = 0;
  vp = c;
  for ( i = 0; i < 3; i++ )
  {
    value = value + *vp;
    vp = vp + 1;
  }
  printf ( "  We get a sum of %d\n", value );

  return 0;
}