extern keyword usage for C language

In the debugger, there is one parameter that needs to be passed between multiple functions because it is used as a debug parameter and does not want to introduce parameters into the function.

It is natural to think of using global variables to represent this common parameter, the structure of the project code is as follows:

MAIN.C test.c test.h

Global variable G_paramter

Create a new Pubparamter.h file:

The contents are as follows:

#ifndef _pubparamter_h_

#

extern keyword usage for C language