How to pass macro definition from “makefile” command line arguments to C source code?

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#FILENAME:Makefile




export SAI=y

 

ifeq ($(SAI),y)

CFLAGS += -DSAI

endif

 

all:

    @gcc $(CFLAGS) macro_test.c -o macro_test

　　

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/*FILENAME:macro_test.c*/

#include <stdio.h>

#include <stdlib.h>

 

int

main(int argc, char* argv[])

{

#ifdef SAI

    printf("I am in SAI env\n");

#endif

 

    printf("hi everyone\n");

 

    return 0;

}

　　

在Makefile中  把

export SAI=y or SAI=n

就可以決定有沒有定義SAI在C code中