CODEWITHSUNDEEP
c
Chrusciki
Chrusciki

Reputation: 115

How do include header files function

Ok, so how I understand #include works is by looking up what you are including and complies that and replaces it where the include is. however, when I assume this, my program doesn't compile and it gives __ is undefined all over the place.

for example when in my main.c will have something like

#include "tim.h"
#include "tim_cfg.h"
#include "tim_api.h"

tim.h contains some typesdefs like

typedef enum
{
RATE_DIV1 = 0X0,
RATE_DIV2 = 0X1,
RATE_DIV3 = 0X2,
RATE_DIV4 = 0X3,
RATE_DIV5 = 0X4,
RATE_DIV6 = 0X5,
RATE_DIV7 = 0X6,
RATE_DIV8 = 0X7,
RATE_DIV9 = 0X8
} BaseRate_T;

typedef unsigned char byte;

tim_cfg.h contains register locations and basic structs

typedef struct
{
byte  TimerSize;         
byte  InterruptLevel;    
} TIMInfo_T;

and tim_api.h contains the function prototypes of the tim functions

So, the problem is why do I get errors 

identifier "byte" is undefined

When it the first thing I include?

Upvotes: 0

Views: 80

Answers (1)

paxdiablo
paxdiablo

Reputation: 881093

You should follow the rule that every header file should include what it needs to work.

With the setup you have, if someone includes tim_cfg.h on its own, the byte type is not defined.

A better solution would be:

tim_cfg.h:
    #include "tim.h"
    typedef struct
    {
        byte  TimerSize;         
        byte  InterruptLevel;    
    } TIMInfo_T;

That way, everything that is needed for tim.cfg.h is there when you include it.

Upvotes: 1

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