C++——Vector

#include "opencv2/objdetect.hpp"                                                                                   
#include "opencv2/videoio.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/imgproc.hpp"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
using namespace std;
using namespace cv;
int main()
{
    std::vector<int> vec;
    vec.push_back(1);
    vec.push_back(2);
    vec.push_back(3);
    vec.push_back(4);
    cout<<vec[3]<<endl;
    vector<int>::iterator it;
    for(it=vec.begin();it!=vec.end();it++){
            cout<<"vector:"<<*it<<endl;
    }
    vec.insert(vec.begin()+3,9);
    cout<<vec[3]<<endl;
    vec.erase(vec.begin()+3);
    cout<<vec[3]<<endl;
    cout<<vec.size()<<endl;

    getch();
    return 0;
}