c++ - 在 C++ 中的类函数下在自身中包含一个类

Question

此代码编译正常并输出 10，但我不确定为什么？

#include <iostream>

class test1 {
  public:
  int getId(){
     test1 t;
     return t.getAnotherId();
  }
  int getAnotherId(){
     return 10;
  }
};

int main(){
   test1 t;
   std::cout << t.getId() << std::endl;
   return 0;
}

在 getId() 下调用时，test1 是否已完全定义？

我问是因为我知道这是无效的，因为类还没有完全定义:

class Node {
    char *cargo;
    Node left;
    Node right;
}

Answer 1

来自规范的 9.2.2:

A class is considered a completely-defined object type (3.9) (or complete type) at the closing } of the class- specifier. Within the class member-specification, the class is regarded as complete within function bodies, default arguments, using-declarations introducing inheriting constructors (12.9), exception-specifications, and brace-or-equal-initializers for non-static data members (including such things in nested classes). Otherwise it is regarded as incomplete within its own class member-specification.

所以在方法体内，类是完整的，可以作为一个完整的类型使用(所以你可以定义一个类类型的局部)。