examples/manual/gslice_array.cpp

/**************************************************************************
 *
 * gslice_array.cpp -- Generalized array slice examples
 *
 * $Id: //stdlib/dev/examples/stdlib/manual/gslice_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;

int main(void) {

  valarray_t::value_type
      ibuf[22] = { 0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  10,
                   11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 };

  // Create a valarray of ints
  valarray_t  vi (ibuf,(sizeof ibuf / sizeof *ibuf));

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

  // Get a two dimensional diagonal slice out of the middle
  std::size_t length_ary[] = {4, 2};
  std::size_t stride_ary[] = {4, 6};

  std::valarray<std::size_t> length_val(length_ary, 2);
  std::valarray<std::size_t> stride_val(stride_ary, 2);


  // Print out the slices starting at positions 0 and 2 and respectively.
  std::cout << "vi[gslice(0,[4,2],[4,6])]\n\n"
            << vi[std::gslice(0,length_val,stride_val)] << "\n\n";

  std::cout << "vi[gslice(2,[4,2],[4,6])]\n\n"
            << vi[std::gslice(2,length_val,stride_val)] << "\n\n";

  // Multiply the first slice by the second.
  vi[std::gslice(0,length_val,stride_val)]
      *= static_cast<valarray_t > (vi[std::gslice(2,length_val,stride_val)]);

  std::cout << "vi[gslice(0,[4,2],[4,8])] *= vi[gslice(2,[4,2],[4,6])]\n\n"
            << vi << std::endl;

  return 0;

}