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- .. Copyright David Abrahams 2006. Distributed under the Boost
- .. Software License, Version 1.0. (See accompanying
- .. file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- Example
- .......
- This example prints an array of characters, using
- ``indirect_iterator`` to access the array of characters through an
- array of pointers. Next ``indirect_iterator`` is used with the
- ``transform`` algorithm to copy the characters (incremented by one) to
- another array. A constant indirect iterator is used for the source and
- a mutable indirect iterator is used for the destination. The last part
- of the example prints the original array of characters, but this time
- using the ``make_indirect_iterator`` helper function.
- ::
- char characters[] = "abcdefg";
- const int N = sizeof(characters)/sizeof(char) - 1; // -1 since characters has a null char
- char* pointers_to_chars[N]; // at the end.
- for (int i = 0; i < N; ++i)
- pointers_to_chars[i] = &characters[i];
- // Example of using indirect_iterator
- boost::indirect_iterator<char**, char>
- indirect_first(pointers_to_chars), indirect_last(pointers_to_chars + N);
- std::copy(indirect_first, indirect_last, std::ostream_iterator<char>(std::cout, ","));
- std::cout << std::endl;
- // Example of making mutable and constant indirect iterators
- char mutable_characters[N];
- char* pointers_to_mutable_chars[N];
- for (int j = 0; j < N; ++j)
- pointers_to_mutable_chars[j] = &mutable_characters[j];
- boost::indirect_iterator<char* const*> mutable_indirect_first(pointers_to_mutable_chars),
- mutable_indirect_last(pointers_to_mutable_chars + N);
- boost::indirect_iterator<char* const*, char const> const_indirect_first(pointers_to_chars),
- const_indirect_last(pointers_to_chars + N);
- std::transform(const_indirect_first, const_indirect_last,
- mutable_indirect_first, std::bind1st(std::plus<char>(), 1));
- std::copy(mutable_indirect_first, mutable_indirect_last,
- std::ostream_iterator<char>(std::cout, ","));
- std::cout << std::endl;
- // Example of using make_indirect_iterator()
- std::copy(boost::make_indirect_iterator(pointers_to_chars),
- boost::make_indirect_iterator(pointers_to_chars + N),
- std::ostream_iterator<char>(std::cout, ","));
- std::cout << std::endl;
- The output is::
- a,b,c,d,e,f,g,
- b,c,d,e,f,g,h,
- a,b,c,d,e,f,g,
- The source code for this example can be found `here`__.
- __ ../example/indirect_iterator_example.cpp
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