int fun ( int a, int *b );

int main ( void )
{
  int i = 1, j = 2;
  int k;

  k = fun ( i, &j );

  return ( 0 );
}

int fun ( int a, int *b )
{
  if ( 1 == a )
  {
    *b = *b + a;
  }
  else
  {
    *b = *b - a;
  }

  return;         //违背1
}