C结构体嵌套

struct Inner;

struct Outer
{
    long id;
    
    struct Inner *inner;
    
};

struct Inner 
{
    long seq;
};

int main(int argc, char const *argv[])
{
    struct Outer outer = {112123};

    printf("%lu
", sizeof(outer.id));
    return 0;
}

丢在使用Struct后定义细节的 Struct 需要提前声明 “

struct Inner；

”