本文档来源于：http://wiki.ros.org/ROS/Tutorials/WritingPublisherSubscriber%28c%2B%2B%29
roscd begginner_tutorials
先创建一个src目录用于存放源代码：
mkdir -p src
然后在其中创建一个talker.cpp源文件，并将如下内容粘贴其中（代码解读见其中的中文注释）。
/*
* Copyright (C) 2008, Morgan Quigley and Willow Garage, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the names of Stanford University or Willow Garage, Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
// %Tag(FULLTEXT)%
// %Tag(ROS_HEADER)%
//Comment by spy: ros/ros.h为ros系统基本功能所需的头文件
#include "ros/ros.h"
// %EndTag(ROS_HEADER)%
// %Tag(MSG_HEADER)%
//Comment by spy: std_msgs/String.h为std_msgs包中的一个消息头文件，由String.msg文件生成
#include "std_msgs/String.h"
// %EndTag(MSG_HEADER)%
#include <sstream>
/**
* This tutorial demonstrates simple sending of messages over the ROS system.
*/
int main(int argc, char **argv)
{
/**
* The ros::init() function needs to see argc and argv so that it can perform
* any ROS arguments and name remapping that were provided at the command line.
* For programmatic remappings you can use a different version of init() which takes
* remappings directly, but for most command-line programs, passing argc and argv is
* the easiest way to do it. The third argument to init() is the name of the node.
*
* You must call one of the versions of ros::init() before using any other
* part of the ROS system.
*/
// %Tag(INIT)%
// 初始化ROS，这允许我们通过命令行进行重命名，也在该出指定我们的节点名，该命名需要在ROS系统下面唯一的（不能重名）
// 该命名不能含有斜杠（/）。
ros::init(argc, argv, "talker");
// %EndTag(INIT)%
/**
* NodeHandle is the main access point to communications with the ROS system.
* The first NodeHandle constructed will fully initialize this node, and the last
* NodeHandle destructed will close down the node.
*/
// %Tag(NODEHANDLE)%
// 创建一个节点句柄，该句柄作为节点进程的句柄，第一次创建时实际上初始化节点，最后一个析构时会释放资源。
ros::NodeHandle n;
// %EndTag(NODEHANDLE)%
/**
* The advertise() function is how you tell ROS that you want to
* publish on a given topic name. This invokes a call to the ROS
* master node, which keeps a registry of who is publishing and who
* is subscribing. After this advertise() call is made, the master
* node will notify anyone who is trying to subscribe to this topic name,
* and they will in turn negotiate a peer-to-peer connection with this
* node. advertise() returns a Publisher object which allows you to
* publish messages on that topic through a call to publish(). Once
* all copies of the returned Publisher object are destroyed, the topic
* will be automatically unadvertised.
*
* The second parameter to advertise() is the size of the message queue
* used for publishing messages. If messages are published more quickly
* than we can send them, the number here specifies how many messages to
* buffer up before throwing some away.
*/
// %Tag(PUBLISHER)%
// 该句告诉master主控节点，我们将在chatter主题中发布std_msgs的String消息，在我们发布消息时，
// 主控节点将会告知所有订阅该主题的节点，消息队列大小为1000，即在队列里有消息超过1000个之后，才会丢弃以前老的消息
ros::Publisher chatter_pub = n.advertise<std_msgs::String>("chatter", 1000);
// %EndTag(PUBLISHER)%
// %Tag(LOOP_RATE)%
// 指定运行频率为10hz，在调用Rate::sleep()之前都会运行。
ros::Rate loop_rate(10);
// %EndTag(LOOP_RATE)%
/**
* A count of how many messages we have sent. This is used to create
* a unique string for each message.
*/
// %Tag(ROS_OK)%
int count = 0;
// 在ros::ok返回true的时候，持续运行，返回false的时候，中断，在以下情况下返回false：
// 1.收到中断信号，SIGINT，键盘输入Ctrl+C会触发中断信号。
// 2.被同名节点从网络上踢出。
// 3.程序的其他部分调用了ros::shutdown()。
// 4.所有的ros::NodeHandles被销毁。
while (ros::ok())
{
// %EndTag(ROS_OK)%
/**
* This is a message object. You stuff it with data, and then publish it.
*/
// %Tag(FILL_MESSAGE)%
// 使用标准消息填充一个字符串。
std_msgs::String msg;
std::stringstream ss;
ss << "hello world " << count;
msg.data = ss.str();
// %EndTag(FILL_MESSAGE)%
// %Tag(ROSCONSOLE)%
// ROS下的输出语句，代替std::cout标准输出。见ros信息级别小节。
ROS_INFO("%s", msg.data.c_str());
// %EndTag(ROSCONSOLE)%
/**
* The publish() function is how you send messages. The parameter
* is the message object. The type of this object must agree with the type
* given as a template parameter to the advertise<>() call, as was done
* in the constructor above.
*/
// %Tag(PUBLISH)%
// 发布消息
chatter_pub.publish(msg);
// %EndTag(PUBLISH)%
// 当添加一个订阅时，ros::spinOnce()会保证，你可以触发回调函数(callback)，如果没有该语句，则不会触发。
// %Tag(SPINONCE)%
ros::spinOnce();
// %EndTag(SPINONCE)%
// %Tag(RATE_SLEEP)%
// 休眠以确保10hz运行。
loop_rate.sleep();
// %EndTag(RATE_SLEEP)%
++count;
}
return 0;
}
// %EndTag(FULLTEXT)%
该文件也可以在github如下路径中找到：https://raw.github.com/ros/ros_tutorials/kinetic-devel/roscpp_tutorials/talker/talker.cpp
大致步骤如下：
ros::init(argc, argv, "talker");
ros::NodeHandle n;
ros::Publisher chatter_pub = n.advertise<std_msgs::String>("chatter", 1000);
指定频率循环发送。
/*
* Copyright (C) 2008, Morgan Quigley and Willow Garage, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the names of Stanford University or Willow Garage, Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
// %Tag(FULLTEXT)%
#include "ros/ros.h"
#include "std_msgs/String.h"
/**
* This tutorial demonstrates simple receipt of messages over the ROS system.
*/
// %Tag(CALLBACK)%
// 接收到主题消息时的回调函数
void chatterCallback(const std_msgs::String::ConstPtr& msg)
{
ROS_INFO("I heard: [%s]", msg->data.c_str());
}
// %EndTag(CALLBACK)%
int main(int argc, char **argv)
{
/**
* The ros::init() function needs to see argc and argv so that it can perform
* any ROS arguments and name remapping that were provided at the command line.
* For programmatic remappings you can use a different version of init() which takes
* remappings directly, but for most command-line programs, passing argc and argv is
* the easiest way to do it. The third argument to init() is the name of the node.
*
* You must call one of the versions of ros::init() before using any other
* part of the ROS system.
*/
// 初始化：指定节点名称。
ros::init(argc, argv, "listener");
/**
* NodeHandle is the main access point to communications with the ROS system.
* The first NodeHandle constructed will fully initialize this node, and the last
* NodeHandle destructed will close down the node.
*/
// 创建节点句柄
ros::NodeHandle n;
/**
* The subscribe() call is how you tell ROS that you want to receive messages
* on a given topic. This invokes a call to the ROS
* master node, which keeps a registry of who is publishing and who
* is subscribing. Messages are passed to a callback function, here
* called chatterCallback. subscribe() returns a Subscriber object that you
* must hold on to until you want to unsubscribe. When all copies of the Subscriber
* object go out of scope, this callback will automatically be unsubscribed from
* this topic.
*
* The second parameter to the subscribe() function is the size of the message
* queue. If messages are arriving faster than they are being processed, this
* is the number of messages that will be buffered up before beginning to throw
* away the oldest ones.
*/
// %Tag(SUBSCRIBER)%
// 订阅指定主题，并指定回调函数，1000为队列大小，当我们来不及处理消息时，会存储在该队列中，若队列元素大于1000，则会抛弃老的消息
ros::Subscriber sub = n.subscribe("chatter", 1000, chatterCallback);
// %EndTag(SUBSCRIBER)%
/**
* ros::spin() will enter a loop, pumping callbacks. With this version, all
* callbacks will be called from within this thread (the main one). ros::spin()
* will exit when Ctrl-C is pressed, or the node is shutdown by the master.
*/
// %Tag(SPIN)%
// spin会进入循环，并在有消息到达时处理消息，Ctrl+C会结束该循环，或者主控节点关闭该节点时也会结束循环。
ros::spin();
// %EndTag(SPIN)%
return 0;
}
// %EndTag(FULLTEXT)%
add_executable(talker src/talker.cpp)
target_link_libraries(talker ${catkin_LIBRARIES})
add_dependencies(talker beginner_tutorials_generate_messages_cpp)
add_executable(listener src/listener.cpp)
target_link_libraries(listener ${catkin_LIBRARIES})
add_dependencies(listener beginner_tutorials_generate_messages_cpp)
这些代码会将上述两个节点加入编译为可执行程序，并指定所需链接库和依赖。
然后执行catkin_make，代码如下：
# In your catkin workspace $ cd ~/catkin_ws $ catkin_make
编译成功显示如下：
Base path: /home/shao/catkin_ws Source space: /home/shao/catkin_ws/src Build space: /home/shao/catkin_ws/build Devel space: /home/shao/catkin_ws/devel Install space: /home/shao/catkin_ws/install #### #### Running command: "make cmake_check_build_system" in "/home/shao/catkin_ws/build" #### #### #### Running command: "make -j8 -l8" in "/home/shao/catkin_ws/build" #### [ 0%] Built target std_msgs_generate_messages_eus [ 0%] Built target std_msgs_generate_messages_lisp [ 0%] Built target std_msgs_generate_messages_nodejs [ 0%] Built target std_msgs_generate_messages_py [ 0%] Built target std_msgs_generate_messages_cpp [ 0%] Built target _begginner_tutorials_generate_messages_check_deps_AddTwoInts [ 0%] Built target _begginner_tutorials_generate_messages_check_deps_Num [ 5%] Generating EusLisp code from begginner_tutorials/Num.msg [ 11%] Generating EusLisp manifest code for begginner_tutorials [ 17%] Generating EusLisp code from begginner_tutorials/AddTwoInts.srv [ 23%] Generating Javascript code from begginner_tutorials/Num.msg [ 29%] Generating C++ code from begginner_tutorials/AddTwoInts.srv [ 35%] Generating C++ code from begginner_tutorials/Num.msg [ 41%] Generating Python from MSG begginner_tutorials/Num [ 47%] Generating Lisp code from begginner_tutorials/Num.msg [ 52%] Generating Javascript code from begginner_tutorials/AddTwoInts.srv [ 58%] Generating Lisp code from begginner_tutorials/AddTwoInts.srv [ 64%] Generating Python code from SRV begginner_tutorials/AddTwoInts [ 64%] Built target begginner_tutorials_generate_messages_nodejs [ 64%] Built target begginner_tutorials_generate_messages_lisp [ 70%] Generating Python msg __init__.py for begginner_tutorials [ 76%] Generating Python srv __init__.py for begginner_tutorials [ 76%] Built target begginner_tutorials_generate_messages_cpp [ 88%] Building CXX object begginner_tutorials/CMakeFiles/talker.dir/src/talker.cpp.o [ 88%] Building CXX object begginner_tutorials/CMakeFiles/listener.dir/src/listener.cpp.o [ 88%] Built target begginner_tutorials_generate_messages_py [ 88%] Built target begginner_tutorials_generate_messages_eus [ 88%] Built target begginner_tutorials_generate_messages [ 94%] Linking CXX executable /home/shao/catkin_ws/devel/lib/begginner_tutorials/talker [ 94%] Built target talker [100%] Linking CXX executable /home/shao/catkin_ws/devel/lib/begginner_tutorials/listener [100%] Built target listener
roscore
然后运行talker节点：
rosrun beginner_tutorials talker
出现发布信息：
运行listener节点：
rosrun beginner_tutorials listener
出现接收界面：
运行成功。好久不见，hello world。
ROS学习笔记10-写一个简单的订阅者和发布者（C++版本）
原文：https://www.cnblogs.com/spyplus/p/11564266.html