Store machine hostname at compile time

Hi g33kz!
I saw some apps, which storred machine hostname at build time. I am coding one project in C, and I want to store machine hostname, where the binary was compiled. I cannot find it. How can I do it? Is there some preprocessor macro or what? I am using gcc.
Thanks

>>9
shit: shit.c
    $(CC) -o $@ $(CFLAGS) -DHOSTNAME=`hostname` $<