Re: Macro to check header define value

[emmanuel]

 Le jeu 21/01/10 17:58, "Peter Johansson" address@hidden a écrit:
> Hi emannuel,
> 
> emmanu
> address@hidden wrote:
> Hi,
> >
> > my software uses an extern library which has its
> version number in it header.h like following:
> #define LIB_VERSION 424242
> >
> > I need to check this version number (because the API
> was changed and this introduced an incompatibility).
>
> > I think about something like
> AC_CHECK_DEFINE_VALUE... bug nothing like that seems to exist.
>
> > Does someone knows how to do that?
> >
> >   
> I would use a more low-level macro such as AC_COMPILE_IFELSE, e.g., as
> 
follows (not tested)
> 
> AC_COMPILE_IFELSE(
> [AC_LANG_PROGRAM(address@hidden:@include <header.h>],
> [ #if LIB_VERSION >= 424242
> // OK
> #else
> # error version too old
> #endif
> ])
> ],
> [ACTION-IF_OK], ACTION-IF_NOT_OK])
> 
> Cheers,
> Peter

Thank you Peter, you helped me a lot.
This is code I have done to check libmicrohttpd version:

       AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
                                        #include <stdint.h>
                                        #include <stdlib.h>
                                        #include <stdio.h>
                                        #include <unistd.h>
                                        #include <microhttpd.h>
                                        ]],
                                        [[
                                        #if MHD_VERSION >= 0x00040000
                                        // MHD_VERSION is high enough
                                        #else
                                        #  MHD_VERSION is to low
                                        #endif
                                        ]])],
                                        [], [AC_MSG_ERROR([[The libmicrohttpd 
version must be 0.4.0 or higher.]])])

Regards
Emmanuel