Question

ERRORS:

1) _counter already defined error

2) one or more multiply defined symbols found

structure.h:

extern int counter = 0; 

List.c:

in one method i increment the counter.

++counter; 

in another method i set the counter to a value within an object
llist->taskID = counter;

Messages.c:

use counter for while loop

while(counter < 1)
{
     //do stuff
}

why does this error occur? I did a ctrl F and searched for all the instances i use counter… these are the only instances i use it…

Answer 1

Your header file structure.h should only have a declaration (not a definition), like:

  extern int counter;

One (only) of the implementation files, conventionally the *.c file containing main, should have a definition like

  int counter = 0;