macr condition compile

背景:

    原来知道条件编程这回事,但从来没用过.现在需要了,而且要从Makefile获取宏.感觉不错,做以下记录.

正文:

Macro condition compile

1. macro check in source code

e.g. main.c

#ifdef MACRO1

  #include "header1.h"

#endif

#ifdef MACRO2

  #indlcude "header2.h"

#endif

2. send macro by Makefile

  include Makefile.in

  gcc -D $MAC -o $OBJ $SRC  #-D means define a macro

3. define macro in Makefile.in

MAC="MACRO1"

4. generate Makefile.in

write a bash or perl script to generate a fit Makefile.in file(multiple macros), in general this script 

is named configure and is executable.