A simple example of how to use iterators in C++11

iteratortest.cpp

/*
 * iteratortest.cpp
 * This file is part of iteratortest.cpp
 *
 * Copyright (C) 2014 - Giacomo Bergami
 *
 * iteratortest.cpp is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * iteratortest.cpp is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with iteratortest.cpp. If not, see <http://www.gnu.org/licenses/>.
 */

 

#include <iostream>
#include <vector>
 
using namespace std;
struct elem {
	int value;
};
typedef vector<struct elem> Vector;

//This adapter increments the Vector::const_iterator, and returns only the field named `value`
//in order to hide the whiole `struct elem`
class Iter
{
    public:
    Iter (Vector::const_iterator begin)
        : start( begin )
    { }

    bool operator!= (const Iter& other) const {
        return start != other.start;
    }
 
    int operator* () const {
    	return start->value;
    }
 
    const Iter& operator++ () {
        ++start; 
        return *this;
    }
 
    private:
    Vector::const_iterator start;
};

// The object over which you should iterate, should provide a begin and an end method, that return two adapters named Iter
class VectorIterable
{
    public:
    VectorIterable (Vector vec) : v{vec} {}
 

    Iter begin () const {
        return Iter(v.begin());
    }
 
    Iter end () const {
        return Iter(v.end());
    }

 
    private:
   	Vector v;
};
 
 
// sample usage of VectorIterable as an interface to get only the field named `value` in the iteration
int main()
{
    struct elem a, b, c;
    a.value = c.value = 1;
    b.value = 2;
    Vector vec;
    vec.push_back(a);
    vec.push_back(b);
    vec.push_back(c);
    for (int i: VectorIterable(vec)) { 
    	std::cout << i << std::endl;
    }
    // Output:
    // 1
    // 2
    // 1
    
}