c++ - 默认构造函数为空时做什么？

Question

我想知道是否有人可以解释分配内存后默认的 ctor 做了什么，它如何初始化分配的内存？

Answer 1

默认构造函数调用所有非静态数据成员的默认构造函数，除了那些保持未初始化的内置类型。

[2003: 12.1/5]:

A default constructor for a class X is a constructor of class X that can be called without an argument. If there is no user-declared constructor for class X, a default constructor is implicitly declared.

[2003: 12.1/8]:

Default constructors are called implicitly to create class objects of static or automatic storage duration (3.7.1, 3.7.2) defined without an initializer (8.5).