a.cc

#include <iostream>
#include <map>
#include <vector>
#include <string>
#include <set>

using namespace std;

template <typename T, typename U>
ostream& operator<<(ostream& os, const pair<T, U> p) {
    os << p.first << ':' << p.second;
    return os;
}

template <typename T, typename Alloc,
          template <typename _1, typename _2> class Container>
ostream& operator<<(ostream& os, const Container<T, Alloc >& p) {
    typename Container<T, Alloc>::const_iterator e = p.end();
    os << '[';
    for (typename Container<T, Alloc>::const_iterator it = p.begin(); it != e;) {
        os << *it;
        os << (++it == e ? "" : ", ");
    }
    os << ']';
    return os;
}

template <typename T, typename Alloc,
          template <typename _1, typename _2, typename _3> class Container>
ostream& operator<<(ostream& os, const Container<T, less<T>, Alloc>& p) {
    typename Container<T, less<T>, Alloc>::const_iterator e = p.end();
    os << '[';
    for (typename Container<T, less<T>, Alloc>::const_iterator it = p.begin(); it != e;) {
        os << *it;
        os << (++it == e ? "" : ", ");
    }
    os << ']';
    return os;
}

template <typename T, typename Alloc,
          template <typename _1, typename _2, typename _3> class Container>
ostream& operator<<(ostream& os, const Container<T, greater<T>, Alloc>& p) {
    typename Container<T, greater<T>, Alloc>::const_iterator e = p.end();
    os << '[';
    for (typename Container<T, greater<T>, Alloc>::const_iterator it = p.begin(); it != e;) {
        os << *it;
        os << (++it == e ? "" : ", ");
    }
    os << ']';
    return os;
}

template <typename T, typename U, typename Compare, typename Alloc,
          template <typename _1, typename _2, typename _3, typename _4> class Container>
ostream& operator<<(ostream& os, const Container<T, U, Compare, Alloc>& p) {
    typename Container<T, U, Compare, Alloc>::const_iterator e = p.end();
    os << '{';
    for (typename Container<T, U, Compare, Alloc>::const_iterator it = p.begin(); it != e; ) {
        os << *it;
        os << (++it == e ? "" : ", ");
    }
    os << '}';
    return os;
}

int main() {
    vector<int> ary;
    ary.push_back(1);
    ary.push_back(2);
    ary.push_back(3);
    cout << ary << endl;        // [1, 2, 3]

    set< string > lis1;
    lis1.insert("foo");
    lis1.insert("bar");
    lis1.insert("baz");
    cout << lis1 << endl;       // [bar, baz, foo]

    map<int, vector<int> > lis2;
    lis2.insert(make_pair(1, ary));
    ary.pop_back();
    lis2.insert(make_pair(2, ary));
    ary.clear();
    lis2.insert(make_pair(3, ary));
    cout << lis2 << endl;       // {1:[1, 2, 3], 2:[1, 2], 3:[]}
}