random() and srandom() unresolved links

[ozmanbozman]

Hi all
I'm writing a software to be compiled and run on C++ BuilderX. I'm using the standard random generators functions random() and srandom() in my program.here is how I declare these using precompiler directives to support cross-platform behavior:

           				// "standard" random number generators
#ifdef USING_SGI			// SGI versions
extern "C" long random(void);
extern "C" void srandom(unsigned);
#endif
#ifdef USING_SUNOS5			// SUNOS5 versions
extern "C" int random(void);
extern "C" int srandom(unsigned);
#endif
#ifdef  USING_CBX
/*support for CBX platform*/

 extern "C"  int random(void);
 extern "C"  void srandom(unsigned);
#endif

when i build my program i got theses link errors :

Error: Unresolved external 'srandom(unsigned int)' referenced from C:\CPPBUILDERX\ANN_0.2\WINDOWS\DEBUG_BUILD\RAND.OBJ
Error: Unresolved external 'random()' referenced from C:\CPPBUILDERX\ANN_0.2\WINDOWS\DEBUG_BUILD\RAND.OBJ
 ILINK32 exited with error code: 2
Build cancelled due to errors

I guess the problem is in the prototype declarations :

extern "C"  int random(void);
  extern "C"  void srandom(unsigned);

I can't figure out what are the prototypes of random() and srandom() in windows Borland c++ Builder X

any Ideas ?
please help !

thanks

[Danny]

You're right. These are not the standard functions. The standard ones are random and srand. In C++ Builder they are declared as follows:

#include <stdlib.h>
int random(int num);

srand(unsigned seed);

I believe that BuilderX uses the same declarations and libraries.

If that doesn't work, try rand() and srand() respectively:

//from stdlib.h
int _RTLENTRY _EXPFUNC rand(void);

void _RTLENTRY _EXPFUNC srand(unsigned __seed);

The problem is that random() and srandom() are implemented as macros that wrap rand() and srand() so the linker can't find them.

BTW, unless you're using a C compiler and a .c file extension, there's no need to wrap these functions with the extern "C" declaration.

[ozmanbozman]

thanks for replying !
the problem is that i'm only doing a porting work for a c++ lib that was written for unix system.I have to add windows borland support . so I added the precompiler diretive :

#ifdef  USING_CBX
/*support for CBX platform*/

 extern "C"  int random(void);
 extern "C"  void srandom(unsigned);
#endif

can u tell me how can i adjust the above code so the linker could recognize random and srandom ?
many thnx

[jonnin]

I think its rand and srand..

globally search and replace (the best option, in my opinion, because this standardizes the code instead of applying a bandaid)

or:

Just do this:
inline int random ()
{
return rand();
}

inline void srand(int seed)
{
srand(seed);
}

or you can #define the names if you prefer
#define random rand
#define srandom srand

[ozmanbozman]

or you can #define the names if you prefer
#define random rand
#define srandom srand

this one works fine !
my program now can build successfully !
many thanks to jonnin and for u all guys !

[ozmanbozman]

Guys I still want your precious help for my ongoing project!

the compilating of my c++ lib was successful using the borland win32 compiler tools toolsets.

I'm now attempting to compile it for the Minimalist GNU compiler for windows toolset : It didn't compiled !
some of the strange errors i got are like :

"stdio.h": C:/CBuilderX/mingw/include/stdio.h type specifier omitted for parameter ` at line 216
"stdio.h": C:/CBuilderX/mingw/include/stdio.h parse error before `)' token at line 379

what could be the source of these errors ? how to fix them ?
many thnx indeed

[Danny]

Well, we can't guess what's going on in lines 216 and 379 without seeing them...
Anyway, try to see if there's a macro masking problem which causes these functions to be replaced by macros. You want to re-read my first post. It explains this potentail problem clealry. Also, make sure that your files have the right extension .

[ozmanbozman]

I will note here that i had the same problem when i first compiled for the Borland win32 compiler tools ...I adjusted an option about files extensions (i'm using .cc) and it worked...
I guess that my problem with Min GNU compiler is also about file extensions; but i can't find any option about this under MINGNU compiler options !
do u have any experience about settin these options for borland c++ builderx?

thnx

[Danny]

File -> New File then in the Create New File Menu choose the .c extension.

Also make sure that the "Perform C++ compilation regardless of file extension" option is disabled. (It is by default). It's located at:

Project-> Build Options Explorer Options -> Compile Mode

[ozmanbozman]

File -> New File then in the Create New File Menu choose the .c extension.

Also make sure that the "Perform C++ compilation regardless of file extension" option is disabled. (It is by default). It's located at:

Project-> Build Options Explorer Options -> Compile Mode

there is no "compile Mode" option for Minimalist GNU compiler toolset !
borland win32 compiler toolset does have this option !
I can't figure out the real cause of my problem...what i know is that MINGW compiler is unable to preprocess even the first header file included in my program : "stdio.h" ...
another question : do i have to install Mingw or is it shiped and installed with CBX distribution?
any ideas?
thanks

[jonnin]

I have no idea. Try modern headers <cstdio> and see if that works?

[Danny]

and btw, it isn't "stdio.h" but <stdio.h>. There is a difference between the two with respect to the default search path. Also, as jonnin said, try <csdtio> instead, unless this is a strictly C program, with the proper file extensions.
I believe you have to install the MINGW compiler engine. C++ BuilderX supports additional compilers but it doesn't install them for you (which I found very annoying when I reveiwed this product a while ago here on DevX).

[ozmanbozman]

and btw, it isn't "stdio.h" but <stdio.h>. There is a difference between the two with respect to the default search path. Also, as jonnin said, try <csdtio> instead, unless this is a strictly C program, with the proper file extensions.
I believe you have to install the MINGW compiler engine. C++ BuilderX supports additional compilers but it doesn't install them for you (which I found very annoying when I reveiwed this product a while ago here on DevX).

I tried what u suggested but without success :-(
when i tried mingw compiler toolset with a simple program it worked ; but it doesn't work for my quit large c++ library !
this stuff is driving me crazzy !

[ozmanbozman]

Hint :
why my library compiled with borland win32 compiler toolset but not with mingw toolset ?

[jonnin]

Because the code is fine and the compiler is improperly installed or configured.