Global variable definitions

[rolfz]

Can anyone help me to understand where I need to put global variables ?

I try to declare simple variable like this transparent to all source code.

int radio_ch[8];
char ch_index;

In a header file I call in main: it works.
Directly in main .c code, I get an error that the variables are undeclared
In header in both .c files I get an error of Identifiers redefined.

So do not realy understand the logic behind. I would expect that a variable not defined within a routine is considered as global.
Thanks for any feedback
Rolfz

[rolfz]

Looks like this was not a successful call for help.

Found the following.

Including strict header file with subroutines and global variables helps.
extern on global variable seems to answer my question

extern int radio_ch[8];
extern int ch_index;

BR
Rolfz

[rolfz]

Thanks to Srdjan

Problem solved,

variable definition in core routine
int radio_ch[8];
int ch_index;

extern definition in all others.
extern int radio_ch[8];
extern int ch_index;

many thanks
Rolfz