front_insert_iterator : custom iterater « STL Algorithms Iterator « C++ Tutorial

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

/* 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 <list>
#include <algorithm>

using namespace std;

/* 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;
}

int main()
{
    list<int> coll;

    // create front inserter for coll
    // - inconvenient way
    front_insert_iterator<list<int> > iter(coll);

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

    PRINT_ELEMENTS(coll);

    // create front inserter and insert elements
    // - convenient way
    front_inserter(coll) = 44;
    front_inserter(coll) = 55;

    PRINT_ELEMENTS(coll);

    // use front inserter to insert all elements again
    copy (coll.begin(), coll.end(),    // source
          front_inserter(coll));       // destination

    PRINT_ELEMENTS(coll);
}

3 2 1
55 44 3 2 1
1 2 3 44 55 55 44 3 2 1