UGN Security Forums UGN Security: Knowledge Base Programming C/C++ extern in cpp

When using the extern is it similar to the define funtion only the extern's first variable is the variable already declared in a headerfile included above and the second part is the new name for easier codding of newer objects and things like that.
The first time I saw it all it said was:
I had no idea, and still don't what this did. While looking at some direct draw I saw some variables like:
I looked in the ddraw.h file and found that so I think I am correct in what extern does, in part anyway.

PS: I think I may have a keylogger of some sort, I don't think it is activly sending information but it is fairly annoying that everytime I hit enter I lose the focus of ALL windows, even full screen games. I don't see any unusual activity but I'd like to get rid of this annoyance.

Global variables are available to all parts of the program. If the existence of a global variable in one file is declared using the extern keyword in another file, the data is available for use by the second file.

So extern is used to use global variables in more than one program from a single file: IE header files?

extern is used to use global variables IN one program that consists of more than one .C or .CPP file.

hi guys im new here