c++ 指定长度容器元素的拷贝移动（copy_backward）

#include <iostream>     // cout
#include <algorithm>    // copy_backward
#include <vector>       // vector
using namespace std;
int main () {
    vector<int> myvector;

    // set some values:
    for (int i=; i<=; i++)
        myvector.push_back(i*);          // myvector: 10 20 30 40 50

    myvector.resize(myvector.size()+);  // allocate space for 3 more elements

    copy_backward ( myvector.begin()+, myvector.begin()+, myvector.end() );

    cout << "myvector contains:";
    for (vector<int>::iterator it=myvector.begin(); it!=myvector.end(); ++it)
        cout << ' ' << *it;
    cout << '\n';

    return ;
}