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Conditional compilation

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  Conditional compilation ashu <ashutosh.ghildiyal@gmail.com> - 2012-02-20 09:57 -0800
    Re: Conditional compilation Ian Collins <ian-news@hotmail.com> - 2012-02-21 07:42 +1300
    Re: Conditional compilation Shao Miller <sha0.miller@gmail.com> - 2012-02-20 14:52 -0500
    Re: Conditional compilation Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-02-20 14:52 -0500

#17684 — Conditional compilation

Hi all, I have a very trivial problem with conditional compilation. I
have a header file called
wrapper.h which is like the global header file for my project. In this
header file I want to define a conditional compilation tag called
DEBUG. This file wrapper.h includes several other files called demo1.h
demo2.c etc. as follows.

/***** wrapper.h****/

#define DEBUG
#include demo1.h
#include demo2.h
.......

/*****end of wrapper.h**/

Now if I try to use the conditional compilation flag DEBUG in any of
these included files, like demo1.h or demo2.h I get an error and the
compilation fails.

/**** demo1.h ***/
# if defined (DEBUG)
#define BASE_ADDRESS
#endif

/***end of demo1.h***/

Can someone help me and point to me my mistake ? The compilation error
is BASE_ADDRESS undeclared and I am using GCC.

regards

/***end of demo1.h**/

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#17685

On 02/21/12 06:57 AM, ashu wrote:
> Hi all, I have a very trivial problem with conditional compilation. I
> have a header file called
> wrapper.h which is like the global header file for my project. In this
> header file I want to define a conditional compilation tag called
> DEBUG. This file wrapper.h includes several other files called demo1.h
> demo2.c etc. as follows.
>
> /***** wrapper.h****/
>
> #define DEBUG
> #include demo1.h
> #include demo2.h
> ........
>
> /*****end of wrapper.h**/
>
> Now if I try to use the conditional compilation flag DEBUG in any of
> these included files, like demo1.h or demo2.h I get an error and the
> compilation fails.
>
> /**** demo1.h ***/
> # if defined (DEBUG)
> #define BASE_ADDRESS
> #endif
>
> /***end of demo1.h***/
>
> Can someone help me and point to me my mistake ? The compilation error
> is BASE_ADDRESS undeclared and I am using GCC.
>
> regards
>
> /***end of demo1.h**/

Showing the actual error and the code where it occurs would help.

-- 
Ian Collins

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#17689

On 2/20/2012 12:57, ashu wrote:
>
> Now if I try to use the conditional compilation flag DEBUG in any of
> these included files, like demo1.h or demo2.h I get an error and the
> compilation fails.
>
> /**** demo1.h ***/
> # if defined (DEBUG)
> #define BASE_ADDRESS
> #endif
>
> /***end of demo1.h***/
>
> Can someone help me and point to me my mistake ? The compilation error
> is BASE_ADDRESS undeclared and I am using GCC.
>
> regards
>
> /***end of demo1.h**/
>

It looks to me like you are forgetting to provide an alternative and are 
using 'BASE_ADDRESS' somewhere in the code regardless of whether or not 
'DEBUG' is defined.

#if defined (DEBUG)
#  define BASE_ADDRESS value_when_debugging_is_enabled
#else
#  define BASE_ADDRESS value_when_debugging_is_disabled
#endif

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#17691

On 2/20/2012 12:57 PM, ashu wrote:
> Hi all, I have a very trivial problem with conditional compilation.

     Since you haven't solved it, how do you know it's trivial?

> /***** wrapper.h****/
>
> #define DEBUG
> #include demo1.h
> #include demo2.h

     Missing some punctuation here, probably " marks.

> /*****end of wrapper.h**/
>
> Now if I try to use the conditional compilation flag DEBUG in any of
> these included files, like demo1.h or demo2.h I get an error and the
> compilation fails.
>
> /**** demo1.h ***/
> # if defined (DEBUG)
> #define BASE_ADDRESS
> #endif
>
> /***end of demo1.h***/
>
> Can someone help me and point to me my mistake ? The compilation error
> is BASE_ADDRESS undeclared and I am using GCC.

     Please post a short and *complete* example of your problem.
What you've provided above is (1) insufficient to support a
diagnosis, and (2) quite clearly not the code the compiler saw.

     Good thing the problem's trivial, right?

-- 
Eric Sosman
esosman@ieee-dot-org.invalid

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