The short version

  int c3 = 1;
  int c5 = 1;
  for ( int i = 1; i <= 100; i++, c3++, c5++ ){

	if ( c3 == 3 ){ printf( "FIZZ" ); c3 = 0; }

	if ( c5 == 5 ){ printf( "BUZZ" ); c5 = 0; }

	if ( c3 && c5 ){ printf( "%d", i ); }
  }