顺序容器元素的定义、输出、排序

#include <iostream>
#include <vector>
#include <iterator>
#include <algorithm>

struct Area {
    Area():x(0), y(0) {}
    Area(int a, int b):x(a),y(b){}
    int x,y;
    bool operator<(const Area &rhs) { return x<rhs.x; } //排序用到
    friend ostream& operator<<(ostream &out, const Area &rhs);  //输出用到  
};

ostream& operator<<(ostream &out, const Area &rhs)
{
    out << "["<< rhs.x <<"," << rhs.y << "]";
    return out;
}

int _tmain(int argc, _TCHAR* argv[])
{
    vector<Area> vec;
    vec.push_back(Area(7,2));
    vec.push_back(Area(5,6));
    vec.push_back(Area(1,8));
    copy(vec.begin(), vec.end(), ostream_iterator<Area>(cout, " "));
    cout << endl;
    sort(vec.begin(), vec.end());
    copy(vec.begin(), vec.end(), ostream_iterator<Area>(cout, " "));
    cout << endl;
}

The copy() function copies the elements between start and end to dest.
ostream_iterator<Area>(cout, " "):定义输出流迭代器