The reading position of the turtlebot3 configuration item in the source code

hello everyone
I have a question about the source code of turbobot3
For example: in turbobot3_ The. yaml file in the slam package stores related configuration items
Then I want to know where these configuration items are read in the source code??

By launching the slam node, each parameter will be read in the launch configuration as below.
Parameters in the yaml files are predefined in each slam method.

Thank you for your answer. I have one more question:

He reads the entire configuration file here. Where are each configuration item used (in the source code? Or in the firmware?)

Hi @L001103

Please refer to the gmapping ROS package.
The parameters section describes the use of defined params.