Bool state is incorrect when retrieved from param server

asked 2014-09-29 07:32:12 -0500

GuoliangLiu
36 ●2 ●2 ●6

updated 2020-08-25 23:10:21 -0500

M@t

2327 ●55 ●80 ●81

The code is:

ros::NodeHandle nh_private("~");     
bool state=false;

nh_private.param<bool>("state", state, "false");

It turns out the "state" is "true". Why???

Comments

Following the answer from @kmhallen, this would seem to be expected (and correct) behaviour (you're just using the wrong type for your default value). Perhaps change your topic title to reflect this?

gvdhoorn ( 2014-09-29 09:56:18 -0500 )edit

add a comment

answered 2014-09-29 08:38:25 -0500

kmhallen
1411 ●13 ●19 ●35

template<typename T>
void param(const std::string& param_name, T& param_val, const T& default_val) const;

From the function prototype, param_val and default_val are both the template type, in this case bool.

The string value "false" is a pointer to the characters 'false' which is non-zero. This is interpreted as true when used as a bool. Try without quotes around false;

nh_private.param<bool>("state", state, false);

edit flag offensive delete link

Comments

great! thinks!

GuoliangLiu ( 2014-10-07 20:25:47 -0500 )edit

I am getting the following error on ROS Noetic. Any ideas?

error: expected primary-expression before ‘bool’
   nh.getParam<bool>("dissemination_rules", dissemination_rules, true);

GPereira ( 2020-07-27 14:12:42 -0500 )edit

The getParam method does not have a default setting parameter (and does not require templating) like the param method.

So if you want to be able to set a default value then use the param method: nh.param<bool>("dissemination_rules", dissemination_rules, true);

Or if you want to just use getParam without setting a default value: nh.Param("dissemination_rules", dissemination_rules);

dwyackzan ( 2022-07-11 10:40:56 -0500 )edit

add a comment

Bool state is incorrect when retrieved from param server

Comments

1 Answer

Comments

Question Tools

Stats

Related questions

Bool state is incorrect when retrieved from param server edit

Comments

1 Answer

Comments

Question Tools

Stats

Related questions

Bool state is incorrect when retrieved from param server