69 lines
2.7 KiB
C++
69 lines
2.7 KiB
C++
/**************************************************************************
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*
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* slice_array.cpp -- Valarray slice array examples
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*
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* $Id: slice_array.cpp 550991 2007-06-26 23:58:07Z sebor $
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*
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***************************************************************************
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed
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* with this work for additional information regarding copyright
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* ownership. The ASF licenses this file to you under the Apache
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* License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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* implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*
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* Copyright 1994-2006 Rogue Wave Software.
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*
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**************************************************************************/
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#include <iostream> // for cout, endl
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#include <valarray.h> // Includes valarray and provides stream inserter.
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#include <examples.h> // Generic header for all examples.
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typedef std::valarray<int> valarray_t;
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int main(void) {
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valarray_t::value_type ibuf[9] = {0,1,2,3,4,5,6,7,8};
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// Create a valarray initialized to the sequence of integers above.
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valarray_t vi (ibuf,9);
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std::cout << "original valarray vi\n\n" << vi << "\n\n";
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// Display a slice of the valarray.
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std::cout << "vi[slice(0,3,3)]\n\n" << vi[std::slice(0,3,3)] << "\n\n";
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// Unfortunately, slice_arrays were not designed to be easily combined.
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// An explicit conversion to valarray is required, leaving us with
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// this awkward casting syntax.
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vi[std::slice (0,3,3)] = static_cast<valarray_t>(vi[std::slice (1,3,3)]) +
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static_cast<valarray_t>(vi[std::slice (2,3,3)]);
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// The operation above uses slices ([0-2],3,3) to treat our valarray
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// as a 3-dimensional array:
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//
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// 0 1 2 3 = 1 + 2
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// 3 4 5 9 = 4 + 5
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// 6 7 8 15 = 7 + 8
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// | | | | | |
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// | | --slice(2,3,3) | | -slice_array for arithmetic operand.
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// | ----slice(1,3,3) | -----slice_array for arithmetic operand.
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// ------slice(0,3,3) ----slice_array assignment refers to valarray.
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std::cout << "vi[slice(0,3,3)] = vi[slice(1,3,3)] + vi[slice(2,3,3)]\n\n"
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<< vi << std::endl;
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return 0;
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}
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