Question

I have an ErrorLog class, that is used to write and modify log files. I’d like to write to it before and after major events for debugging purposes and I only want to use one instance of the ErrorLog class for the entire application. I tried declaring an ErrorLog object as a global by placing

ErrorLog exe_log;

into a header file so it is accessbile to other files, but I keep getting an error saying it is already defined. Is there a correct way to defing global objects?

Answer 1

You need a declaration in a header file and a definition in a source file.

foo.h:

extern ErrorLog exe_log;   // declaration (note the "extern")

foo.cpp:

ErrorLog exe_log;          // definition

bar.cpp:

#include "foo.h"