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How to publish messages on a topic of type rosgraph_msgs/Clock?

asked 2017-04-24 09:33:30 -0500

manupe94 gravatar image

updated 2017-04-24 11:35:59 -0500


I want to give values to a topic with this type of mesage (rosgraph_msgs/Clock)

I create a variable called "reloj" for example:

rosgraph_msgs::Clock reloj;

How do I give a value to that variable?, because it has two parts (secs and nsecs)

For example in float64 I give it the value this way

std_msgs::Float64 variable; = 0;

I would like to do the same but in rosgraph_msgs/Clock, one value for "secs" and one for "nsecs"

I tried: reloj.clock.secs = 1; reloj.clock.nsecs = 100;

reloj.clock_secs = 1; reloj.clock_nsecs = 100;

But this does not work

I found that putting the following does work

reloj.clock = {5,88};

but when creating the node executable, I get this warning:

warning: extended initializer lists only available with -std=c++11 or -std=gnu++11 reloj.clock = {5,88};

I use ROS kinetic and roscpp (c++)

this is the code in c++

#include "ros/ros.h"
#include "rosgraph_msgs/Clock.h"
rosgraph_msgs::Clock reloj;
int main(int argc, char **argv)
ros::init(argc, argv, "pubsubclock");
ros::NodeHandle n;
ros::Publisher publicador;
publicador  = n.advertise<rosgraph_msgs::Clock>("topico_pub", 1000);
reloj.clock = {5,88};
ros::Rate loop_rate(10);
while (ros::ok()) {
return 0;

thank you very much

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But this does not work

that doesn't tell us very much. Please explain what you found that "does not work". Include any error messages that you get.

Please use the edit button/link to update your original question.

gvdhoorn gravatar imagegvdhoorn ( 2017-04-24 10:03:25 -0500 )edit

I updated the message

manupe94 gravatar imagemanupe94 ( 2017-04-24 11:33:54 -0500 )edit

The syntax reloj.clock = {5,88}; is a form of constructor calling that is new in C++11. You cannot use it without telling the compiler to compile in C++11 mode.

Geoff gravatar imageGeoff ( 2017-04-24 20:07:47 -0500 )edit

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answered 2017-04-24 20:13:17 -0500

Geoff gravatar image

The rosgraph_msgs::Clock message definition field clock has the msg data type time. In C++ this maps to the ros::Time class. You need to use that class to work with it. For example:

reloj.clock = ros::Time(1, 100);
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Asked: 2017-04-24 09:33:30 -0500

Seen: 867 times

Last updated: Apr 24 '17