两个文件:
主文件: a1.c

#include <stdio.h>
#include "a2.c"

int main(void)
{
    printf("print a1.c");

    return 0;
}


另外一个文件: a2.c
void test(void)
{
    printf("a2.c");
}


编译出错:
f:\test\abc\a2.c||In function `test':|
f:\test\abc\a2.c|3|warning: implicit declaration of function `printf'|
obj\Debug\a1.o||In function `test':|
f:\test\abc\a2.c|2|multiple definition of `_test'|
obj\Debug\a2.o:f:\test\abc\a2.c|2|first defined here|
||=== Build finished: 2 errors, 1 warnings ===|


请怎么回事？？