我创建了以下3个文件:
unit1.c
#include <stdio.h>
static int a=30;
void printtest1()
{
printf("unit1 variable a = %d\n", a);
}
unit2.c
#include <stdio.h>
extern int a;
void printtest2()
{
printf("unit2 variable a = %d\n",a);
}
main.c
#include "unit1.c"
#include "unit2.c"
int main(int argc, char *argv[])
{
printtest1();
printtest2();
return 0;
}
这些代码都运行的很正常,没有任何问题:
unit1 variable a = 30
unit2 variable a = 30
我的疑问是,理论上不是应该会报错吗?因为在unit1.c中a是被标识为static的,只能在unit1.c中被访问,为什么unit2.c中可以extern的到?
然后我把main中的
#include "unit1.c"
#include "unit2.c"
调换一下顺序,改成
#include "unit2.c"
#include "unit1.c"
编译器就会正常报错了
In file included from main.c:2:
unit1.c:2:12: error: static declaration of ‘a’ follows non-static declaration
static int a=30;
^
In file included from main.c:1:
unit2.c:3:12: note: previous declaration of ‘a’ was here
extern int a;
^
求解