Date: Wed, 30 Dec 2009 08:17:52 +0100 From: Oliver Mahmoudi <olivermahmoudi@gmail.com> To: "freebsd-questions@FreeBSD.org" <freebsd-questions@freebsd.org> Subject: how does the C pre-processor interface with make? Message-ID: <6b4b2d2c0912292317h7c4d9bbfo196dcf48396e0afa@mail.gmail.com>
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Hey folks, I was wondering how the C pre-processor interfaces with make. Let's suppose that I have a little C program, something along the lines of: #include <stdio.h> int main() { #ifdef FOO fprintf(stdout, "Hi, my name is foo.\n"); #endif #ifdef BAR fprintf(stdout, "Hi, my name is bar.\n"); #endif fprintf(stdout, "I am always here.\n"); return(1-1); } It is easy to control the pre-processor in the above code by defining the respective terms or leaving them out, however, I am trying to control the conditionals from out of a makefile. This is essentially the way in which the kernel sources are compiled. Any suggestions? Thanks Oliver
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