Create back_insert_iterator : custom iterater « STL Algorithms Iterator « C++

1. C++
2. STL Algorithms Iterator
3. custom iterater

Create back_insert_iterator

 
 

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include <iostream>
#include <vector>
#include <algorithm>

/* PRINT_ELEMENTS()
 * - prints optional C-string optcstr followed by
 * - all elements of the collection coll
 * - separated by spaces
 */
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
    typename T::const_iterator pos;

    std::cout << optcstr;
    for (pos=coll.begin(); pos!=coll.end(); ++pos) {
        std::cout << *pos << ' ';
    }
    std::cout << std::endl;
}

using namespace std;

int main()
{
    vector<int> coll;

    // create back inserter for coll
    // - inconvenient way
    back_insert_iterator<vector<int> > iter(coll);

    // insert elements with the usual iterator interface
    *iter = 1;
    iter++;
    *iter = 2;
    iter++;
    *iter = 3;
    PRINT_ELEMENTS(coll);

    // create back inserter and insert elements
    // - convenient way
    back_inserter(coll) = 44;
    back_inserter(coll) = 55;
    PRINT_ELEMENTS(coll);

    // use back inserter to append all elements again
    // - reserve enough memory to avoid reallocation
    coll.reserve(2*coll.size());
    copy (coll.begin(), coll.end(),    // source
          back_inserter(coll));        // destination
    PRINT_ELEMENTS(coll);
}

/* 
1 2 3
1 2 3 44 55
1 2 3 44 55 1 2 3 44 55

 */        
  

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