examples/manual/indirect_array.cpp

/**************************************************************************
 *
 * indirect_array.cpp -- Indirect array examples
 *
 * $Id: //stdlib/dev/examples/stdlib/manual/indirect_array.cpp#13 $
 *
 ***************************************************************************
 *
 * Copyright (c) 1994-2005 Quovadx,  Inc., acting through its  Rogue Wave
 * Software division. Licensed under the Apache License, Version 2.0 (the
 * "License");  you may  not use this file except  in compliance with the
 * License.    You    may   obtain   a   copy   of    the   License    at
 * http://www.apache.org/licenses/LICENSE-2.0.    Unless   required    by
 * applicable law  or agreed to  in writing,  software  distributed under
 * the License is distributed on an "AS IS" BASIS,  WITHOUT WARRANTIES OR
 * CONDITIONS OF  ANY KIND, either  express or implied.  See  the License
 * for the specific language governing permissions  and limitations under
 * the License.
 * 
 **************************************************************************/

#include <iostream>    // for cout, endl
#include <valarray.h>  // Includes valarray and provides stream inserter.
#include <examples.h>  // Generic header for all examples.

typedef std::valarray<int>    valarray_t;
typedef std::valarray<std::size_t> selector_t;

int main(void) {

  // Create a valarray of integers.
  valarray_t::value_type vbuf[10] = {0,1,2,3,4,5,6,7,8,9};
  valarray_t vi(vbuf, (sizeof vbuf / sizeof *vbuf));

  // Create a valarray of indices for a selector.
  selector_t::value_type sbuf[6] = {0,2,3,4,7,8};
  selector_t selector(sbuf, (sizeof sbuf / sizeof *sbuf));

  // Print out the valarray<int>.
  std::cout << "original valarray vi\n\n" << vi << "\n\n";

  // Print out the selective array.
  std::cout << "vi[0,2,3,4,7,8]\n\n" <<  vi[selector] << "\n\n";

  // Double the selected values.
  vi[selector] += vi[selector];

  // Print out the modified valarray.
  std::cout << "vi[0,2,3,4,7,8] += vi[0,2,3,4,7,8]\n\n" << vi << std::endl;

  return 0;
}