Re: [Mingw-users] Undefined reference to 'getaddrinfo'

[James S. <jam...@op...>]

On Fri, 2006-08-25 at 07:38 +0200, Michael Gerdau wrote:
> > I have a small c program that calls getaddrinfo and freeaddrinfo.
> > 
> > I have the header file included for ws2tcpip.h.
> > 
> > When I compile with
> > gcc -Wall -o prog main.c -lws2_32
> > 
> > I get warnings about implicit declarations of the 2 functions and
> > undefined references to the 2 functions from the linker.
> > 
> > In the ws2tcpip.h I see
> > #if (_WIN32_WINNT >= 0x0501)
> > 
> > ---declaration of getaddrinfo
> > 
> > #else
> > /* FIXME ...
> > 
> > When I print the value of _WIN32_WINNT I get 0x400 so obviously the
> > function isn't declared.  That explains the implicit declarations
> > warning.  But what about the undefined references?  The functions are in
> > the library ws2_32.a.
> > 
> > What do I need to do to resolve this?  Is it a MinGW version or a
> > Windows version that needs updating?  Or something completely different?
> 
> The lib you link to by providing -lws2_32 is an importlib. Whether that
> contains the required functions of not is pretty irrelevant.
> 
> The question is:
> Does your OS provide them (you didn't tell us the OS you are using). Search
> MSDN for these functions to check which OS versions support them, thereby
> finding out whether your particular environment provides them.

Ah ha.  XP Pro is what the app will need to run on.

> If it doesn't you see why it is wise MinGW is conservative here.
> If it does then define WINVER (not _WIN32_WINNT unless you know what
> you are doing) to 0x0501 at the top of your program.

> FYI this and a few other constants are defined in windef.h.

Thanks for your help.

Regards,
James.