ros2-docs/docs/General ROS 2/Building ROS 2 Packages/ROS 2 Subscriber.md
2024-12-12 15:30:03 -05:00

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# ROS 2 Subscriber
## Sample Code
Here is the code for creating a python node that subscribes to `/robot_news` at 2Hz.
=== "Python"
``` python title="smartphone.py" linenums="1"
#!/usr/bin/env python
import rclpy
from rclpy.node import Node
from example_interfaces.msg import String
class SmartphoneNode(Node):
def __init__(self):
super().__init__("smartphone")
self.subscriber_ = self.create_subscription(String, 'robot_news', self.callback_robot_news, 10)
self.get_logger().info("Smartphone has been starte.")
def callback_robot_news(self, msg):
self.get_logger().info(msg.data)
def main (args=None):
rclpy.init(args=args)
node = SmartphoneNode()
rclpy.spin(node)
rclpy.shutdown()
if __name__ == '__main__':
main()
```
=== "C++"
``` python title="smartphone.cpp" linenums="1"
#include "rclcpp/rclcpp.hpp"
#include "example_interfaces/msg/string.hpp"
class SmartphoneNode : public rclcpp::Node
{
public:
SmartphoneNode() : Node("smartphone")
{
subscriber_ = this->create_subscription<example_interfaces::msg::String>(
"robot_news", 10,
std::bind(&SmartphoneNode::callbackRobotNews, this, std::placeholders::_1));
RCLCPP_INFO(this->get_logger(), "Smartphone has been started.");
}
private:
void callbackRobotNews(const example_interfaces::msg::String::SharedPtr msg)
{
RCLCPP_INFO(this->get_logger(), "%s", msg->data.c_str());
}
rclcpp::Subscription<example_interfaces::msg::String>::SharedPtr subscriber_;
};
int main(int argc, char **argv)
{
rclcpp::init(argc, argv);
auto node = std::make_shared<SmartphoneNode>();
rclcpp::spin(node);
rclcpp::shutdown();
return 0;
}
```