27 #include "ros/ros.h" 28 #include "std_msgs/String.h" 29 30 #include <sstream> 31 32 /** 33 * This tutorial demonstrates simple sending of messages over the ROS system. 34 */ 35 int main(int argc, char **argv) 36 { 37 /** 38 * The ros::init() function needs to see argc and argv so that it can perform 39 * any ROS arguments and name remapping that were provided at the command line. 40 * For programmatic remappings you can use a different version of init() which takes 41 * remappings directly, but for most command-line programs, passing argc and argv is 42 * the easiest way to do it. The third argument to init() is the name of the node. 43 * 44 * You must call one of the versions of ros::init() before using any other 45 * part of the ROS system. 46 */ 47 ros::init(argc, argv, "talker"); 48 49 /** 50 * NodeHandle is the main access point to communications with the ROS system. 51 * The first NodeHandle constructed will fully initialize this node, and the last 52 * NodeHandle destructed will close down the node. 53 */ 54 ros::NodeHandle n; 55 56 /** 57 * The advertise() function is how you tell ROS that you want to 58 * publish on a given topic name. This invokes a call to the ROS 59 * master node, which keeps a registry of who is publishing and who 60 * is subscribing. After this advertise() call is made, the master 61 * node will notify anyone who is trying to subscribe to this topic name, 62 * and they will in turn negotiate a peer-to-peer connection with this 63 * node. advertise() returns a Publisher object which allows you to 64 * publish messages on that topic through a call to publish(). Once 65 * all copies of the returned Publisher object are destroyed, the topic 66 * will be automatically unadvertised. 67 * 68 * The second parameter to advertise() is the size of the message queue 69 * used for publishing messages. If messages are published more quickly 70 * than we can send them, the number here specifies how many messages to 71 * buffer up before throwing some away. 72 */ 73 ros::Publisher chatter_pub = n.advertise<std_msgs::String>("chatter", 1000); 74 75 ros::Rate loop_rate(10); 76 77 /** 78 * A count of how many messages we have sent. This is used to create 79 * a unique string for each message. 80 */ 81 int count = 0; 82 while (ros::ok()) 83 { 84 /** 85 * This is a message object. You stuff it with data, and then publish it. 86 */ 87 std_msgs::String msg; 88 89 std::stringstream ss; 90 ss << "hello world " << count; 91 msg.data = ss.str(); 92 93 ROS_INFO("%s", msg.data.c_str()); 94 95 /** 96 * The publish() function is how you send messages. The parameter 97 * is the message object. The type of this object must agree with the type 98 * given as a template parameter to the advertise<>() call, as was done 99 * in the constructor above. 100 */ 101 chatter_pub.publish(msg); 102 103 ros::spinOnce(); 104 105 loop_rate.sleep(); 106 ++count; 107 } 108 109 110 return 0; 111 }
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