什么是空析构函数？ [英] What does empty destructor do?

问题描述

我听说空析构函数不做任何事情，并且调用它不会删除对象。
但是在代码中：

I heard that empty destructor doesn't do anything and calling it doesn't remove the object. But in the code:

#include <iostream>
#include <set>


class a
{
public:
    ~a() 
    {}
std::set <int> myset;
};

int main()
{
a object;
object.myset.insert(55);
object.~a();
object.myset.insert(20);
std::cout << object.myset.size();
}

我得到：
* glibc detected * / strong> /.app：double free or corruption（fasttop）：and thenABORT。

I get: "* glibc detected * /.app: double free or corruption (fasttop):" and then "ABORT".

如果重要的话我启用了c ++ 11标志。那么什么是空构造函数实际上做什么？

If it matters I have c++11 flag enabled. So what does empty constructor actually do? It does something and I read it doesn't.

推荐答案

你的析构函数可能看起来是空的，但它实际上是破坏了成员变量。在这种情况下，它会破坏 myset ，因此后续的 insert（20）会崩溃。

Your destructor may look empty, but it's actually destructing the member variables. In this case, it's destructing myset, so the subsequent insert(20) is crashing.

如果你的类没有非POD成员变量，那么空析构函数将不会做任何事情。

If your class had no non-POD member variables then the empty destructor would truly do nothing.

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