1 struct Inner;
 2 
 3 struct Outer
 4 {
 5     long id;
 6     
 7     struct Inner *inner;
 8     
 9 };
10 
11 struct Inner 
12 {
13     long seq;
14 };
15 
16 int main(int argc, char const *argv[])
17 {
18     struct Outer outer = {112123};
19 
20     printf("%lu\n", sizeof(outer.id));
21     return 0;
22 }

 

丢在使用Struct后定义细节的 Struct 需要提前声明 “

struct Inner；

”