config variables in config.h

[Viktor Pavlenko]

Hello,

I would like my program to know where it has been installed, in
particular, the location of $datadir. Looks like a natural way to do
it is to have a #define in config.h, like this:

/*
 * myprog data directory
 */
#define MYPROG_DATA_DIR "/usr/local/share/myprog"

I tried the following in configure.in:

AC_DEFINE_UNQUOTED(MYPROG_DATA_DIR,$datadir,[myprog data directory])

but it doesn't work ($prefix/share is inserted and not expanded). I
would appreciate it if someone could tell me how to do this properly.

Thanks in advance.

Viktor