Using C++ libraries in FreeBasic

[angros47]

I've created a library in C++ (Mingw), and exported some functions using extern "C". I then tried to call it from a FreeBasic program (linking it), and I got theese errors:

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.//liblib.a(lib.o):lib.cpp:(.text+0x1e): undefined reference to `std::cout'
.//liblib.a(lib.o):lib.cpp:(.text+0x23): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
.//liblib.a(lib.o):lib.cpp:(.text+0x2b): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)'

...and many others

I tried to copy the stdc++.a, but I got more errors.
I know that FreeBasic can link libraries in the same way as GCC: on C forums, I found no help (the only suggestion was to use G++ instead of GCC, to link all files, or to use a makefile, but this is not a good solution, since I need to use fbc)

Can anybody help me? How can I link a library compiled with C++? Can I "pre-link" it and the C++ run-time, to have a single .a file? If so, how?

[anonymous1337]

Try using #include "crt.bi" (C runtime) at the top of your program.

[srvaldez]

I am no expert at all, just curious, did you compile your lib with g++?

[angros47]

@Printchard:

Tested it, it doesn't work. The problem is, I need some routines that are part of C++ standard library (it should be iostream), and aren't part of FreeBasic. Can they be linked in my library? Or there is another solution?

@srvaldez

Yes, I compiled the library with g++, and made it with ar cr

[Merick]

Were you trying to link stdc++.a into your lib or into the FB code? If the missing function are needed only by your lib's internal functions, then linking stdc++.a into the lib itself when compiling it with mingw should be enough.

[angros47]

If the missing function are needed only by your lib's internal functions, then linking stdc++.a into the lib itself when compiling it with mingw should be enough.

That's exactly what I'd like to do; but how can I do it? the linker allows to create a .a library from many .o files, but not from another .a library.

Can you help me?

[srvaldez]

perhaps this link will help http://www.trilithium.com/johan/2005/06/static-libstdc/ I would be interested if you solve it, had exact same problem with a library I was trying to compile and gave up.

[duke4e]

@Printchard
lol

[stylin]

the linker allows to create a .a library from many .o files, but not from another .a library.

For what it's worth, ar is used to manipulate archives. Try something like

ar -rcs libmylib.a libstdc++.a

and see it's documentation for more details. Hope this helps.

[4quiles]

Sometimes I use C++ libs in Freebasic dll's. The C++ lib usually use some STL stuff, like list or maps. Try doing the following:

Create all the C++ functions with the extern "C" (and of course use only parameters that are recognized by FB).
Copy libstdc++.a from the mingw lib path into the Freebasic lib path
Finally declare the functions in some .bi file:

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#Ifndef __MYFILE_BI__
#define __MYFILE_BI__

#Inclib "stdc++"
#Inclib "MyCppLib"

Extern "Windows-MS" 

Declare Function SomeCppFunction(...) as Integer
Declare Function ...

End Extern

#EndIf  ' __MYFILE_BI__

[anonymous1337]

@Printchard
lol

Sorry :( I don't have FB installed so I (probably shouldn't have) took a guess.

[angros47]

Sometimes I use C++ libs in Freebasic dll's. The C++ lib usually use some STL stuff, like list or maps. Try doing the following:

Create all the C++ functions with the extern "C" (and of course use only parameters that are recognized by FB).
Copy libstdc++.a from the mingw lib path into the Freebasic lib path
Finally declare the functions in some .bi file:

Tried it, I got a lot of errors:

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.//libstdc++.a(eh_terminate.o):eh_terminate.cc:(.text+0x12): undefined reference to `__cmshared_unexpected'
.//libstdc++.a(eh_terminate.o):eh_terminate.cc:(.text+0x44): undefined reference to `__cmshared_terminate'
.//libstdc++.a(eh_terminate.o):eh_terminate.cc:(.text+0x68): undefined reference to `__cmshared_terminate'
.//libstdc++.a(eh_terminate.o):eh_terminate.cc:(.text+0x84): undefined reference to `__cmshared_unexpected'
.//libstdc++.a(eh_terminate.o):eh_terminate.cc:(.text+0x8b): undefined reference to `__cmshared_terminate'
.//libstdc++.a(eh_catch.o):eh_catch.cc:(.text+0x127): undefined reference to `_Unwind_Resume'
.//libstdc++.a(eh_globals.o):eh_globals.cc:(.text+0x6): undefined reference to `__cmsharedptr'
.//libstdc++.a(eh_globals.o):eh_globals.cc:(.text+0x70): undefined reference to`__cmsharedptr'
.//libstdc++.a(eh_globals.o):eh_globals.cc:(.text+0xc5): undefined reference to`__cmsharedptr'
.//libstdc++.a(eh_globals.o):eh_globals.cc:(.text+0x111): undefined reference to `__cmsharedptr'
.//libstdc++.a(eh_globals.o):eh_globals.cc:(.text+0x12d): undefined reference to `__cmsharedptr'
.//libstdc++.a(eh_globals.o):eh_globals.cc:(.text+0x152): undefined reference to `_Unwind_Resume'
.//libstdc++.a(eh_globals.o):eh_globals.cc:(.text+0x16e): undefined reference to `__cmsharedptr'

[4quiles]

This test is a small library made in Dev C++ using some STL and then is used on Freebasic. The library does not do anything useful... just an example.
Maybe you can compare and see what is not working.

http://www.sendspace.com/file/1i4yp6

P.D: Someone knows an upload site without all that annoying publicity? :)

[angros47]

Tested it: maybe the problem is that I have Mingw 4.3.3, and the example is for version 3?

If I use the library included in the sample, it works, if I try to rebuild it, it doesn't work.

Edit: if I build the library with the given object file, it work: if I recompile c++ code into a new .o file, it doesn't

[dani.user]

Compile the library as a .dll and make sure the functions you export for fb don't return or ask for variabiles from stdc++