今日课堂练习：vector构造函数

#include 
#include 
using namespace std;
void printVector(vector &v)
{
    vector::iterator iter;
    for(iter=v.begin(); iter != v.end(); iter++)
    {
    cout << *iter << " ";
    }
    cout << endl;
}
int main()
{
    vector v;
    v.push_back(10);
    v.push_back(20);
    v.push_back(30);
    v.push_back(40);
    v.push_back(50);
    printVector(v);
    vector v2 = v;
    printVector(v2);
    vector v3(v2.begin()+2, v2.end());
    printVector(v3);
    return 0;
}