Attention: Answers.ros.org is deprecated as of August the 11th, 2023. Please visit robotics.stackexchange.com to ask a new question. This site will remain online in read-only mode during the transition and into the foreseeable future. Selected questions and answers have been migrated, and redirects have been put in place to direct users to the corresponding questions on Robotics Stack Exchange. Additional details are available here.

How do I get the length of a String in C++?

ROS1
C++

asked 2018-02-08 19:05:43 -0600

kylerlaird
104 ●10 ●16 ●20

I'm sending binary data as a String. It's easy to publish it and read it in Python, but I'm trying to extend a driver that's written in C++ (and I have very little C++ experience). I made it work by using this ugly kludge in the topic subscriber.

uint32_t string_length = ros::serialization::serializationLength(*msg) - 4;

I was hoping that there would be a length value in the message but according to http://wiki.ros.org/ROS/Tutorials/Wri... String only has one member, "data". Is there a clean way to get the length of the data?

edit retag flag offensive close merge delete

add a comment

1 Answer

Sort by » oldest newest most voted

answered 2018-02-08 22:45:54 -0600

ahendrix

47576 ●179 ●367 ●662 http://namniart.com/

Similar to python's len() method for determining the length of a string, the std::string object in C++ has a length() member function that returns the length of the string. (See: http://www.cplusplus.com/reference/st... for more complete documentation of std::string)

Since the string in a std_msgs/String message is represented with a std::string in C++, if you have a pointer to a std_msgs::String (the C++ type for std_msgs/String) you can get the string's length with msg->data.length().

edit flag offensive delete link

Comments

Perfect. That is exactly the answer I needed and the reference will help me with other work. I updated the code and it works as expected. Thank you!

kylerlaird ( 2018-02-09 08:04:10 -0600 )edit

add a comment

Question Tools

1 follower

Stats

Asked: 2018-02-08 19:05:43 -0600

Seen: 1,277 times

Last updated: Feb 08 '18

How do I get the length of a String in C++? edit

1 Answer

Comments

Question Tools

Stats

Related questions

How do I get the length of a String in C++?