Question

I want use std::vector.push_bask to store 20 numbers of shared_ptr in a for loop.
But from the output: it seems it only pushed one.
And vector::push_back> 20 times worked as designed.

Could some body help me out?

class IObserver{
public:
    int virtual  notify() = 0;
};

class CAdsUser
{
public:
    int do_ads() {cout << __FUNCTION__<<endl;m_observer->notify(); return 0;}
    CAdsUser(tr1::shared_ptr<IObserver> b):m_observer(b){cout << __PRETTY_FUNCTION__<<endl;};
    ~CAdsUser() {cout << __PRETTY_FUNCTION__<<endl;}
private:
    tr1::shared_ptr<IObserver> m_observer;
};

class CMgr:public IObserver
{
public:
    int virtual notify() { cout << __PRETTY_FUNCTION__<<endl; return 0;};
    virtual ~CMgr(){cout << __PRETTY_FUNCTION__<<endl;};
};

using namespace std;

typedef vector<tr1::shared_ptr<CAdsUser> >VecType;
int main() {
    tr1::shared_ptr<CMgr> g(new CMgr());
    VecType m_online_user;
    int i = 0;
    for(i = 0; i < 20; i++);
    {
        tr1::shared_ptr<CAdsUser> ads_temp(new CAdsUser(g));
        cout <<&ads_temp<<endl;
        m_online_user.push_back((ads_temp));
        //m_online_user.insert(m_online_user.begin(),1,ads_temp);
    }
    tr1::shared_ptr<CAdsUser> ads_temp1(new CAdsUser(g));
    cout <<&ads_temp1<<endl;
    m_online_user.push_back(ads_temp1);

    /// CAdsUser *p =  m_online_user[7];
    VecType::iterator vi;
    for(vi = m_online_user.begin();vi != m_online_user.end(); vi++)
        (*vi)->do_ads();

    vector<tr1::shared_ptr<string> > test_string;
    for(i = 0; i< 20; i++)
    {
        tr1::shared_ptr<string> temp(new string());
        temp->append("sdfsdfsfd");
        test_string.push_back(temp);
    }

    vector<tr1::shared_ptr<string> >::iterator vs;
    for(vs = test_string.begin();vs != test_string.end(); vs++)
        cout<<*(*vs)<<endl;

    return 0;
}

The program output:

CAdsUser::CAdsUser(std::tr1::shared_ptr<IObserver>)
0xbfbf3084
CAdsUser::CAdsUser(std::tr1::shared_ptr<IObserver>)
0xbfbf30a0
do_ads
virtual int CMgr::notify()
do_ads
virtual int CMgr::notify()
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
sdfsdfsfd
CAdsUser::~CAdsUser()
CAdsUser::~CAdsUser()
virtual CMgr::~CMgr()

Answer 1

for(i = 0; i < 20; i++);
                    // ^ this little guy is killing you

Remove that ;, you’ve got a for loop with an empty body.