Re: [Boost-users] Preprocessor thingy

Johan 't Hart wrote:

Hi,

I don't know if boost has a solution for my problem, or there is just something simple I miss... I've been struggling with some preprocessor things. I'm trying to use it for versioning. Here is the problem:

I've got these defines:

#define VERSION_MAJOR 5 #define VERSION_MINOR 4 #define VERSION_BUILD 3 #define VERSION_SUBBUILD 2

Sometimes I just need a string like: "5.4.3.2". I do it like this:

#define STRINGER_(s) #s #define STRINGER(s) STRINGER_(s) #define VERSION_STRING_1 \ STRINGER(VERSION_MAJOR) "." \ STRINGER(VERSION_MINOR) "." \ STRINGER(VERSION_BUILD) "." \ STRINGER(VERSION_SUBBUILD)

So VERSION_STRING_1 is "5.4.3.2" Now I need a string like: "5.4.3b". (Note the 'b'. When VERSION_SUBBUILD == 3, I want it to be a 'c' etc) How do I do this in a preprocessor command???? The char is simple, its (VERSION_SUBBUILD+'a'-1).

You need a lookup table to do it all in the preprocessor, AFAIK: #include #include #define VERSION_ID(major,minor,build,sub_build) \ BOOST_PP_STRINGIZE( \ major.minor.build.BOOST_PP_CAT(N2LCC_,sub_build) ) #define N2LCC_1 a #define N2LCC_2 b #define N2LCC_3 c #define N2LCC_4 d #define N2LCC_5 e #define N2LCC_6 f #define N2LCC_7 g #define N2LCC_8 h #define N2LCC_9 i #define N2LCC_10 j #define N2LCC_11 k #define N2LCC_12 l #define N2LCC_13 m #define N2LCC_14 n #define N2LCC_15 o #define N2LCC_16 p #define N2LCC_17 q #define N2LCC_18 r #define N2LCC_19 s #define N2LCC_20 t #define N2LCC_21 u #define N2LCC_22 v #define N2LCC_23 w #define N2LCC_24 x #define N2LCC_25 y #define N2LCC_26 z VERSION_ID(2,1,3,1) Regards, Tobias