map<int, int> a;

    a[10] = 1;

    a[2] = 2;

    a[30] = 3;

    a[4] = 4;

    a[50] = 5;

    a[32] = 6;

    for(map<int, int>::iterator it = a.begin();it != a.end();it++ )

    {

        LOG(INFO) << "---- key :" << it->first << "value " << it->second;

        a.erase(it);

        break;

    }

    for(map<int, int>::iterator it = a.begin();it != a.end();it++ )

    {

        LOG(INFO) << "end---- key :" << it->first << "value " << it->second;

    }