Hi,
I'm declaring my structs in a seperate .h file like this
I've included the .h file in main so accessing them from main.c is fine. However if I then include this in other files I get errors (redeclaration). Do I need to use extern in the other files when referencing my eQ1 struct?Code:struct { ... } eQ1;
You need to separate the declaration of your struct from the declaration of a variable of that struct type. As written, your struct has no name, so it is impossible to refer to it.
In the .h
In ONE .c file onlyCode:struct foo { int member; }; extern struct foo eQ1;
In all other .c files which use itCode:#include "myheader.h" struct foo eQ1;
Code:#include "myheader.h"
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
Thanks everybody, I've done as you've suggested but I'm still having issues. Now I'm getting 'redeclaration' errors, as a result of include the same header file more than once in my project. I think it's because I haven't set up my project correctly. What I have is
main.c
a.h
b.h
c.h
In a, b and c header files I'm actually doing some work. I've noticed that other projects will have something like this
main.c
a.h
a.c
b.h
b.c
c.h
c.c
Can someone please explain why this is done this way? As you can see by my username, I am a beginner. But I am trying to find out on my own too.
Thanks
putin your header filesCode:#ifndef FILE__H #define FILE__H /* code */ #endif
What does this do/achieve?
if you include the same file twice, it won't redeclare the variables.
Is this a 'best practice' method? I didn't find much info on it on google.
It's what almost everyone does.. Except for compilers supporting the "#pragma once" command.
