C++ STL traverse vector

// Traverse the vector container
#include <iostream>
#include <vector>
using namespace std;

struct ST{
    int id;
    double db;
};

void Origin(int num,vector<ST>& vt){
    int m = num;
    ST temp;
    for(int i=0;i<m;++i){
        temp.id=i+1;
        temp.db=(i+1)*10;
        vt.push_back(temp);
    }
}

void Iter_for(vector<ST>& vt){
    ST temp;
    vector<ST>::iterator iter;
    for(iter=vt.begin();iter!=vt.end();++iter){
        temp=*iter;
        cout<<"id: "<<temp.id<<",db: "<<temp.db<<endl;
    }
}

void at_for(vector<ST>& vt){
    ST temp;
    int i=0;
    int m=vt.size();
    for(i=0;i<m;++i){
        temp = vt.at(i);
        cout<<"id: "<<temp.id<<",db: "<<temp.db<<endl;
    }
}


intmain()
{
    ST tmp;
    vector<ST> myvt;
    Origin(5,myvt);
    int size=myvt.size();
    cout<<"size: "<<size<<endl;
    cout<<"Iterator output!"<<endl;
    Iter_for(myvt);
    at_for(myvt);
    cout<<"empty() usage:"<<endl;
    while(!myvt.empty()){
        tmp=myvt.back();
        cout<<"id: "<<tmp.id<<",db: "<<tmp.db<<endl;
        myvt.pop_back();
    }
    return 0;
}