#include <iostream>
#include <vector>

using namespace std;

int main()
{
    vector<int> arr;
    arr.push_back(6);
    arr.push_back(7);
    arr.push_back(8);
    arr.push_back(9);

    for(vector<int>::iterator it=arr.begin(); it!=arr.end(); )
    {
        if(* it == 8)
        {
            it = arr.erase(it);
        }
        else
        {
            ++it;
        }
    }

    //注意上面不能写成

    /*
        for(vector<int>::iterator it=arr.begin(); it!=arr.end(); it ++)
        {
            if(* it == 8)
            {
                arr.erase(it); //在erase后，it失效，并不是指向vector的下一个元素，it成了一个“野指针”。

            }
        }
      
    */

    cout << "After remove 8:\n";

    for(vector<int>::iterator it = arr.begin(); it < arr.end(); ++it)
    {
        cout << * it << " ";
    }
    cout << endl << arr.size();
    cout << endl;

}