Modular Programming: #include .h file

arga · Joined: 09 Sep 2003 Posts: 22

Consider the following:

In the main file is, among others, included:

#include "test.h"

main()
{
while(TRUE)
{
// code here
// also calls a function declared in test.h
}
}

The test.h file contains a function declaration:
void sample(int, int);

And its implementation is contained in the test.c file:
#include "test.h"
void sample(int x, int y)
{
//code here
}

The compiler generates an error with the following message:
Function used but not defined: sample

Am I missing something or is this a compiler limitation?
___________________________
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Original Post ID: 144517468

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

:=The test.h file contains a function declaration:
:= void sample(int, int);
:=
:=And its implementation is contained in the test.c file:
:= #include "test.h"
:= void sample(int x, int y)
:= {
:= //code here
:= }
:=
:=The compiler generates an error with the following message:
:=Function used but not defined: sample
:=
:=Am I missing something or is this a compiler limitation?
----------------------------------------------------------

With CCS, the function prototype must be exactly the same as
the declaration. (including the variable names).
___________________________
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Original Post ID: 144517469

Mark · Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA

You have to include the test.c file in your main file. You can include the test.h in the test.c file. You should use some #ifdef to prevent the header files from being included more than once.

:=Consider the following:
:=
:=In the main file is, among others, included:
:=
:=#include "test.h"
:=
:=main()
:={
:= while(TRUE)
:= {
:= // code here
:= // also calls a function declared in test.h
:= }
:=}
:=
:=
:=The test.h file contains a function declaration:
:= void sample(int, int);
:=
:=And its implementation is contained in the test.c file:
:= #include "test.h"
:= void sample(int x, int y)
:= {
:= //code here
:= }
:=
:=
:=The compiler generates an error with the following message:
:=Function used but not defined: sample
:=
:=Am I missing something or is this a compiler limitation?
___________________________
This message was ported from CCS's old forum
Original Post ID: 144517470

arga · Joined: 09 Sep 2003 Posts: 22

I have included the #ifndef but just didn't show it.

Not being able to #include the test.h only in the main file goes against true c modular programming. Jut including the test.h file should have sufficed. So, I'm surprised it doesn't work here.

:=You have to include the test.c file in your main file. You can include the test.h in the test.c file. You should use some #ifdef to prevent the header files from being included more than once.
:=
:=
:=:=Consider the following:
:=:=
:=:=In the main file is, among others, included:
:=:=
:=:=#include "test.h"
:=:=
:=:=main()
:=:={
:=:= while(TRUE)
:=:= {
:=:= // code here
:=:= // also calls a function declared in test.h
:=:= }
:=:=}
:=:=
:=:=
:=:=The test.h file contains a function declaration:
:=:= void sample(int, int);
:=:=
:=:=And its implementation is contained in the test.c file:
:=:= #include "test.h"
:=:= void sample(int x, int y)
:=:= {
:=:= //code here
:=:= }
:=:=
:=:=
:=:=The compiler generates an error with the following message:
:=:=Function used but not defined: sample
:=:=
:=:=Am I missing something or is this a compiler limitation?
___________________________
This message was ported from CCS's old forum
Original Post ID: 144517473

arga · Joined: 09 Sep 2003 Posts: 22

:=:=The test.h file contains a function declaration:
:=:= void sample(int, int);
:=:=
:=:=And its implementation is contained in the test.c file:
:=:= #include "test.h"
:=:= void sample(int x, int y)
:=:= {
:=:= //code here
:=:= }
:=:=
:=:=The compiler generates an error with the following message:
:=:=Function used but not defined: sample
:=:=
:=:=Am I missing something or is this a compiler limitation?
:=----------------------------------------------------------
:=
:=With CCS, the function prototype must be exactly the same as
:=the declaration. (including the variable names).

PCM Programmer, I'll try having the variable names in the prototype as well. This really surprises me that the declaration must also have variable names. As we all know in normal Cc just the type in the prototype should suffice.
___________________________
This message was ported from CCS's old forum
Original Post ID: 144517474

arga · Joined: 09 Sep 2003 Posts: 22

:=:=The test.h file contains a function declaration:
:=:= void sample(int, int);
:=:=
:=:=And its implementation is contained in the test.c file:
:=:= #include "test.h"
:=:= void sample(int x, int y)
:=:= {
:=:= //code here
:=:= }
:=:=
:=:=The compiler generates an error with the following message:
:=:=Function used but not defined: sample
:=:=
:=:=Am I missing something or is this a compiler limitation?
:=----------------------------------------------------------
:=
:=With CCS, the function prototype must be exactly the same as
:=the declaration. (including the variable names).

I tried having the function prototype with variable names in the .h file, and the definition in the .c file

In the .c file I #include .h and the function parameters are exactly the same.

In the main program I only #include .h and the compiler still generates the same error message.
___________________________
This message was ported from CCS's old forum
Original Post ID: 144517477

Mark · Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA

There is only one source file for the CCS compiler. It does not compile modules and then link them together. You have to use a slightly different approach.

:=I have included the #ifndef but just didn't show it.
:=
:=Not being able to #include the test.h only in the main file goes against true c modular programming. Jut including the test.h file should have sufficed. So, I'm surprised it doesn't work here.
:=
:=:=You have to include the test.c file in your main file. You can include the test.h in the test.c file. You should use some #ifdef to prevent the header files from being included more than once.
:=:=
:=:=
:=:=:=Consider the following:
:=:=:=
:=:=:=In the main file is, among others, included:
:=:=:=
:=:=:=#include "test.h"
:=:=:=
:=:=:=main()
:=:=:={
:=:=:= while(TRUE)
:=:=:= {
:=:=:= // code here
:=:=:= // also calls a function declared in test.h
:=:=:= }
:=:=:=}
:=:=:=
:=:=:=
:=:=:=The test.h file contains a function declaration:
:=:=:= void sample(int, int);
:=:=:=
:=:=:=And its implementation is contained in the test.c file:
:=:=:= #include "test.h"
:=:=:= void sample(int x, int y)
:=:=:= {
:=:=:= //code here
:=:=:= }
:=:=:=
:=:=:=
:=:=:=The compiler generates an error with the following message:
:=:=:=Function used but not defined: sample
:=:=:=
:=:=:=Am I missing something or is this a compiler limitation?
___________________________
This message was ported from CCS's old forum
Original Post ID: 144517478

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Try the following test program. It compiled without errors
with PCM vs. 3.173, and MPLAB vs. 5.70.20. If it doesn't
work for you, then post your version of the compiler.

The file TEST.H contains only this line:
<PRE>
void sample(int x, int y);
</PRE>

The file TEST.C contains this code:
<PRE>
#include <16F877.h>
#fuses HS, NOWDT, NOPROTECT, PUT, BROWNOUT, NOLVP
#use Delay(clock=8000000)
 
#include "test.h"
 
//========================================================
void main()
{
int a;
int b;
 
a = 0x55;
b = 0xAA;
 
sample(a, b);
 
while(1);
}
 
//------------------------------
 
void sample(int x, int y)
{
int c;
 
c = x + y;
 
}
</PRE>
___________________________
This message was ported from CCS's old forum
Original Post ID: 144517481

arga · Joined: 09 Sep 2003 Posts: 22

Am I correct in my assumption here that the program contains only 2 files, namely, TEST.H and TEST.C. The latter file has the main() function.

If this is correct then I can see why it works. The function definition is written below (and outside) the main().
The function prototype (contained in the TEST.H) is above so the compiler sees it before the main().

The scenario I'm trying to figure out is having 3 files contained in the same directory. A file, let's call it main1.c contains the main(), that #includeS TEST.H. This TEST.H is #includeD in the TEST.C.

I want the TEST.H file only to contain prototypes and all its definitions in a separate file (not in the main file). This makes the main file more "readable". We know that all C textbooks will tell us this is possible. You can even make the variables public by using the word extern.

But somehow the CCS compiler doesn't like it written this way. I'm using CCS C ver. 3.173

/*****************MAIN.C**************************/
#include <16F877.h>

//and so on...

#include "TEST.H" //contained in the same directory
//This is also #includeD in the TEST.C

main()
{
while(1)
{
//code here that also calls the sample() function
}
}
/*****************END OF MAIN.C*********************/

/***************TEST.H******************************/
#ifndef TEST_H
#define TEST_H

void sample( int x, int y );

#endif

/***************END OF TEST.H***********************/

/***************TEST.C*****************************/
#include "TEST.H"

void sample(int x, int y)
{
//handle x and y
}

/***************END OF TEST.C*********************/

-------------------
:=Try the following test program. It compiled without errors
:=with PCM vs. 3.173, and MPLAB vs. 5.70.20. If it doesn't
:=work for you, then post your version of the compiler.
:=
:=
:=The file TEST.H contains only this line:
:=<PRE>
:=void sample(int x, int y);
:=</PRE>
:=
:=
:=The file TEST.C contains this code:
:=<PRE>
:=#include <16F877.h>
:=#fuses HS, NOWDT, NOPROTECT, PUT, BROWNOUT, NOLVP
:=#use Delay(clock=8000000)
:= 
:=#include "test.h"
:= 
:=//========================================================
:=void main()
:={
:=int a;
:=int b;
:= 
:=a = 0x55;
:=b = 0xAA;
:= 
:=sample(a, b);
:= 
:=while(1);
:=}
:= 
:=//------------------------------
:= 
:=void sample(int x, int y)
:={
:=int c;
:= 
:=c = x + y;
:= 
:=}
:=</PRE>
:=
:=
___________________________
This message was ported from CCS's old forum
Original Post ID: 144517486

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

I'm assuming that you want to call the function within main().
Somehow, main() needs to know that the function exists
before you call it. You can do this by putting the function
above main(), which is what CCS does in all their examples.
Or, you can put the function below main(), and put a function
prototype above main().

So, if your function prototype is in test.h, and your function
is in test.c, then your main file should look like this:

<PRE>
#include "test.h" // This file contains the function prototype
 
main()
{
 
sample(1, 2); // Call the function.
 
}
 
#include "test.c" // This file contains the function.
</PRE>

I do all my large programs like this, and it works very well.

Note: I have put the filenames in quotes because the board
wasn't displaying them if I used angle brackets.
___________________________
This message was ported from CCS's old forum
Original Post ID: 144517490

arga · Joined: 09 Sep 2003 Posts: 22

:=I'm assuming that you want to call the function within main().
:=Somehow, main() needs to know that the function exists
:=before you call it. You can do this by putting the function
:=above main(), which is what CCS does in all their examples.
:=Or, you can put the function below main(), and put a function
:=prototype above main().
:=
:=So, if your function prototype is in test.h, and your function
:=is in test.c, then your main file should look like this:
:=
:=<PRE>
:=#include "test.h" // This file contains the function prototype
:= 
:=main()
:={
:= 
:=sample(1, 2); // Call the function.
:= 
:=}
:= 
:=#include "test.c" // This file contains the function.
:=</PRE>
:=
:=I do all my large programs like this, and it works very well.
:=
:=
:=Note: I have put the filenames in quotes because the board
:=wasn't displaying them if I used angle brackets.

Thanks. I do the same, too. And I also looked at CCS' examples and noticed the same, too. I pointed this out to my Visual C++ programmer colleagues and we thought that it is a compiler limitation. But, I wanted to make my programs more transparent. Obviously, this is a limitation.

As I do visual programming as well (in C++ and this is the main focus of the company), the way we do modular programming is in line with normal programming techniques. However, I'm new to embedded C and have only previously done it in Assembly. Hence, I post quite often.

I don't see any advantage of having prototypes in a .h file only to define it in the same file where the main() is defined.

Thanks, PCM Programmer, for all your input.
___________________________
This message was ported from CCS's old forum
Original Post ID: 144517495

arunb · Joined: 08 Sep 2003 Posts: 492 Location: India

Hello,

Is it possible to just declare the header file in the main file just as we do in any other compiler, or is it neccessary to add the ifndef statements.

thanks
arun

Mark · Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA

In my opinion you should always have the

#ifndef SOMEFILE_H
#define SOMEFILE_H
.
.
.
#endif

for every header file. It is just good coding practice.