std::string s("Hello");
std::string f;

// 前两个参数是变换的范围，第三个是变换的起始位置
// 第四个参数为lambda表达式，变换的规则
std::transform(s.begin(), s.end(), s.begin(),
  [](unsigned char c) { return std::toupper(c); });
std::cout <<"after transform, s: "<< s << std::endl;  // HELLO

std::transform( s.begin(), s.end(), std::back_inserter(f),
              [](unsigned char c) { return std::tolower(c); }  );
std::cout << "after transform, f: " << f << std::endl;  // hello

std::copy( s.begin(), s.end(), std::back_inserter(f) );
std::cout << "after copy, f: " << f << std::endl;  // helloHELLO

vector<int> v={1,2,3,4,5,6};
vector<int> s;
copy(v.begin(), v.end(), back_inserter(s) );  // s: 123456

tf2_ros::Buffer buffer_;
tf2_ros::TransformListener listener(buffer_);
buffer_.transform(in_pose, out_pose, frame, transform_duration_);

vector<std::string> params;
std::string file = "123.45.abc.0";
std::istringstream param_stream(file);
std::string param;
while(getline(param_stream, param, '.'))
{
    cout << param <<endl;
    params.push_back(param);
}

bool readCSVInput(int N, vector<double> &input_points_x, vector<double> &input_points_y, vector<double> &anchor_points_x, vector<double> &anchor_points_y)
{
    ifstream readCSV("/home/user/data.csv", ios::in);
    int lineNum = 0;
    string lineString;
    vector<vector<string>> stringArray;
    cout << endl;
    while (getline(readCSV, lineString) )
    {
        //cout << lineString << endl;
        if (lineNum > 0)
        {
            stringstream ss(lineString);
            string s;
            vector<string> oneLineStrings;
            while (getline(ss, s, ',') )
                oneLineStrings.push_back(s);
            if (oneLineStrings.size() != 5)
            {
                cout << "ERROR:oneLineStrings.size() != 5" << endl;
                return false;
            }
            else
            {
                input_points_x.push_back(std::stod(oneLineStrings[1]));
                input_points_y.push_back(std::stod(oneLineStrings[2]));
                anchor_points_x.push_back(std::stod(oneLineStrings[3]));
                anchor_points_y.push_back(std::stod(oneLineStrings[4]));
            }
        }
        lineNum++;
    }
    if (N == input_points_x.size())
    {
        return true;
    }
    else
    {
        input_points_x.clear();
        input_points_y.clear();
        anchor_points_x.clear();
        anchor_points_y.clear();
        cout << "ERROR:N == input_points_x.size()" << endl;
        return false;
    }
}

struct Timespan {
	common::Time start;
	common::Time end;
};
Timespan表征扫描的时间范围。

struct Floor {
	std::vector< Timespan> timespans;
	double z; //z轴的中值
};

int main(int argc, char** argv)
{
    ros::init(argc, argv, "launch_subscribers");
    ros::NodeHandle nh;
    Node node;
    node.LaunchSubscribers("base_scan", 1, "/base_odometry/odom", 1, "/torso_lift_imu/data", 1);
    ros::spin();
}

void Node::LaunchSubscribers(const std::string& scan_topic, const int scan_num,
                             const std::string& odom_topic, const int use_odom,
                             const std::string& imu_topic,  const int use_imu
                            )
{
	if(scan_num)
        LaunchLaserScanSub(scan_topic, scan_num);
    if(use_odom)
        LaunchOdomSub(odom_topic, use_odom);
    if(use_imu)
        LaunchImuSub(imu_topic, use_imu);
}

void Node::LaunchLaserScanSub(const std::string& scan_topic, const int scan_num)
{
    subscribers_.push_back(
      { SubscribeWithHandler<sensor_msgs::LaserScan>(
           &Node::HandleLaserScanMessage, 
           scan_num, scan_topic, &node_handle_, this),
       scan_topic}  );
}

// 这里也可以把 int 改为 bool
template <typename MessageType>
::ros::Subscriber SubscribeWithHandler(
    void (Node::*handler)(int, const std::string&,
                          const typename MessageType::ConstPtr&),
    const int num, const std::string& topic,
    ::ros::NodeHandle* const node_handle, Node* const node)
{
  return node_handle->subscribe<MessageType>(
      topic, 1,
      boost::function<void(const typename MessageType::ConstPtr&)>(
          [node, handler, num,
           topic](const typename MessageType::ConstPtr& msg) {
            (node->*handler)(num, topic, msg);
          })  );
}

// 根据上面的void (Node::*handler)部分，参数依次为int,  string&,  MessageType::ConstPtr&
// scan_num 就是main函数里的1
void Node::HandleLaserScanMessage(int scan_num, const std::string& sensor_id,
                                  const sensor_msgs::LaserScan::ConstPtr& msg)
{
    ROS_INFO("range_min: %f, scan_num: %d", msg->range_min, scan_num );
}