examples/manual/distance.cpp

/**************************************************************************
 *
 * distance.cpp - Example program for distance between two iterators.
 *
 * $Id: //stdlib/dev/examples/stdlib/manual/distance.cpp#14 $
 *
 ***************************************************************************
 *
 * 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 <cassert>
#include <iterator>
#include <iostream>
#include <vector>

#include <examples.h>


int main ()
{
    // Typedefs for convenience.
    typedef std::vector<int, std::allocator<int> > Vector;

    typedef std::ostream_iterator<Vector::value_type,
                                  char,
                                  std::char_traits<char> > os_iter;

    // Initialize a vector using an array.
    const Vector::value_type arr [] = { 3, 4, 5, 6, 7, 8 };
    const Vector v (arr + 0, arr + sizeof arr/ sizeof *arr);

    // Declare a vector iterator, s.b. a ForwardIterator.
    Vector::const_iterator it = v.begin () + 3;

    // Output the original vector.
    std::cout << "For the vector: ";
    std::copy (v.begin (), v.end (), os_iter (std::cout, " "));
    std::cout << '\n';

    std::cout << "\nWhen the iterator is initialized to point to "
              << *it << '\n';

    // Compute the distance of it from the first element.
    Vector::difference_type dist = 0;

#ifndef _RWSTD_NO_EXT_VOID_DISTANCE

    // using the extended overload of function template distance()
    // provided by this implmentation, compute the distance between
    // the two iterators
    std::distance (v.begin (), it, dist);

    assert (3 == dist);

#endif   // _RWSTD_NO_EXT_VOID_DISTANCE

    // do the same using the standard function template distance()
    dist = std::distance (v.begin (), it);

    std::cout << "The distance between the beginning and "
              << *it << " is " << dist << '\n';

    return 0;
}