Programming Forums > Application Development > C++

rsnd · Apr 28th, 2006, 7:17 AM

Yeah...its me trobouling you lot again.

Wots wrong in this:

typedef struct {

		void (__stdcall * StringCallback)(char  * string);

		void (__stdcall * IntCallback)(int eint);

	} CallbacksGalore;

in gcc:

(Toggle Plain Text)

g++ -v
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v --enable-languages=c,c++,java,f95,objc,ada,treelang --prefix=/usr --with-gxx-include-dir=/usr/include/c++/4.0.2 --enable-shared --with-system-zlib --libexecdir=/usr/lib --enable-nls --without-included-gettext --enable-threads=posix --program-suffix=-4.0 --enable-__cxa_atexit --enable-libstdcxx-allocator=mt --enable-clocale=gnu --enable-libstdcxx-debug --enable-java-gc=boehm --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-4.0-1.4.2.0/jre --enable-mpfr --disable-werror --enable-checking=release i486-linux-gnu
Thread model: posix
gcc version 4.0.2 20050808 (prerelease) (Ubuntu 4.0.1-4ubuntu9)

I mean...used to work fine in windows vc++...

Thanks in advance

The Dark · Apr 28th, 2006, 7:41 AM

Good question, whats wrong with it?
If you are getting errors from gcc, why not put them here to save us having to guess.

rsnd · Apr 28th, 2006, 8:46 AM

so gcc is not meant to support function pointers?

nnxion · Apr 28th, 2006, 9:38 AM

Quote:

Originally Posted by rsnd

so gcc is not meant to support function pointers?

Of course it is meant to support them, he meant, post your gcc errors.

grumpy · Apr 28th, 2006, 10:48 AM

__stdcall is a compiler specific extension (specific to vc++ and a couple of other compilers that target windows, anyway) not supported by gcc.

rsnd · Apr 28th, 2006, 8:43 PM

But its supposed to work on linux!!! http://www.programmersheaven.com/2/Calling-conventions

grumpy · Apr 28th, 2006, 10:08 PM

Even if you accept that link as definitive (which I don't), it describes calling conventions supported by compilers, not the means of tickling a compiler to use them.

In any event, there is no point in bleating if a compiler complains when you try to use something like __stdcall. __stdcall is openly a compiler specific extension. In this Microsoft did the right thing: names with one or more leading underscores fall into a set reserved by the C and C++ standards for compiler specific extensions. There is no requirement for other compilers to support such extensions.

Your solution is to remove the __stdcall qualifier.

If you want to be sensitive to compilers (or, more accurately, libraries that insist on using extensions like __stdcall) that require you to use __stdcall, then use macros to help.

(Toggle Plain Text)

#if defined(WHATEVER_MACRO_IDENTIFIES_YOUR_COMPILER)
#define STDCALL __stdcall
#elif defined (__GNUG__)     /*  gcc  IIRC */
#define STDCALL
#endif

typedef struct {

		void (STDCALL * StringCallback)(char  * string);

		void (STDCALL * IntCallback)(int eint);

	} CallbacksGalore;

Personally, I wouldn't do it this way as it sprinkles compiler dependencies into all functions that use your CallbacksGalore type, but this is one quick fix for amateurs.

Apr 28th, 2006, 7:17 AM	#1
rsnd Hobbyist Programmer Join Date: Jun 2005 Location: Helltown Posts: 162 Rep Power: 4	GCC Linux question Yeah...its me trobouling you lot again. Wots wrong in this: (Toggle Plain Text) typedef struct { void (__stdcall * StringCallback)(char * string); void (__stdcall * IntCallback)(int eint); } CallbacksGalore; typedef struct { void (__stdcall * StringCallback)(char * string); void (__stdcall * IntCallback)(int eint); } CallbacksGalore; in gcc: (Toggle Plain Text) g++ -v Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --enable-languages=c,c++,java,f95,objc,ada,treelang --prefix=/usr --with-gxx-include-dir=/usr/include/c++/4.0.2 --enable-shared --with-system-zlib --libexecdir=/usr/lib --enable-nls --without-included-gettext --enable-threads=posix --program-suffix=-4.0 --enable-__cxa_atexit --enable-libstdcxx-allocator=mt --enable-clocale=gnu --enable-libstdcxx-debug --enable-java-gc=boehm --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-4.0-1.4.2.0/jre --enable-mpfr --disable-werror --enable-checking=release i486-linux-gnu Thread model: posix gcc version 4.0.2 20050808 (prerelease) (Ubuntu 4.0.1-4ubuntu9) g++ -v Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --enable-languages=c,c++,java,f95,objc,ada,treelang --prefix=/usr --with-gxx-include-dir=/usr/include/c++/4.0.2 --enable-shared --with-system-zlib --libexecdir=/usr/lib --enable-nls --without-included-gettext --enable-threads=posix --program-suffix=-4.0 --enable-__cxa_atexit --enable-libstdcxx-allocator=mt --enable-clocale=gnu --enable-libstdcxx-debug --enable-java-gc=boehm --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-4.0-1.4.2.0/jre --enable-mpfr --disable-werror --enable-checking=release i486-linux-gnu Thread model: posix gcc version 4.0.2 20050808 (prerelease) (Ubuntu 4.0.1-4ubuntu9) I mean...used to work fine in windows vc++... Thanks in advance __________________ Spread your wings and fly! Chicken!

Apr 28th, 2006, 8:46 AM	#3
rsnd Hobbyist Programmer Join Date: Jun 2005 Location: Helltown Posts: 162 Rep Power: 4	so gcc is not meant to support function pointers? __________________ Spread your wings and fly! Chicken!

Apr 28th, 2006, 8:43 PM	#6
rsnd Hobbyist Programmer Join Date: Jun 2005 Location: Helltown Posts: 162 Rep Power: 4	But its supposed to work on linux!!! http://www.programmersheaven.com/2/Calling-conventions __________________ Spread your wings and fly! Chicken!

Apr 28th, 2006, 10:08 PM	#7
grumpy Programming Guru Join Date: Jun 2005 Location: Adelaide, South Australia Posts: 1,260 Rep Power: 5	Even if you accept that link as definitive (which I don't), it describes calling conventions supported by compilers, not the means of tickling a compiler to use them. In any event, there is no point in bleating if a compiler complains when you try to use something like __stdcall. __stdcall is openly a compiler specific extension. In this Microsoft did the right thing: names with one or more leading underscores fall into a set reserved by the C and C++ standards for compiler specific extensions. There is no requirement for other compilers to support such extensions. Your solution is to remove the __stdcall qualifier. If you want to be sensitive to compilers (or, more accurately, libraries that insist on using extensions like __stdcall) that require you to use __stdcall, then use macros to help. (Toggle Plain Text) #if defined(WHATEVER_MACRO_IDENTIFIES_YOUR_COMPILER) #define STDCALL __stdcall #elif defined (__GNUG__) /* gcc IIRC / #define STDCALL #endif typedef struct { void (STDCALL StringCallback)(char * string); void (STDCALL * IntCallback)(int eint); } CallbacksGalore; #if defined(WHATEVER_MACRO_IDENTIFIES_YOUR_COMPILER) #define STDCALL __stdcall #elif defined (__GNUG__) /* gcc IIRC / #define STDCALL #endif typedef struct { void (STDCALL StringCallback)(char * string); void (STDCALL * IntCallback)(int eint); } CallbacksGalore; Personally, I wouldn't do it this way as it sprinkles compiler dependencies into all functions that use your CallbacksGalore type, but this is one quick fix for amateurs.

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Apr 28th, 2006, 7:41 AM	#2
The Dark Expert Programmer Join Date: Jun 2005 Posts: 893 Rep Power: 4	Good question, whats wrong with it? If you are getting errors from gcc, why not put them here to save us having to guess.

Apr 28th, 2006, 10:48 AM	#5
grumpy Programming Guru Join Date: Jun 2005 Location: Adelaide, South Australia Posts: 1,260 Rep Power: 5	__stdcall is a compiler specific extension (specific to vc++ and a couple of other compilers that target windows, anyway) not supported by gcc.

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