如何在C++中清理已删除的对象

bob*_*bob 7 c++

是否可以将C++中已删除对象的内存清零?我想这样做是为了在单元测试中重现一个coredump:

//Some member variable of object-b is passed-by-pointer to object-a
//When object-b is deleted, that member variable is also deleted
//In my unit test code, I want to reproduce this
//even if I explicitly call delete on object-b
//accessBMemberVariable should coredump, but it doesn't
//I'm assuming even though object-b is deleted, it's still intact in memory
A *a = new A();
{
  B *b = new B(a);
  delete b;
}
a->accessBMemberVariable();
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bee*_*f2k 20

您可能应该覆盖delete运算符.

给定B类的示例:

class B
{
public:

  // your code
  ...

  // override delete
  void operator delete(void * p, size_t s)
  {
    ::memset(p, 0, s);
    ::operator delete(p, s);
  }
};
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编辑:谢谢litb指出这一点.

  • 不好.在内部运算符delete()中,析构函数已被调用.这将再次调用它. (3认同)
  • jmucchiello是对的.delete运算符将调用析构函数,然后它将调用您的运算符delete.在其中,您应该将内存归零,然后委托给全局运算符delete(using :: operator delete(p);).@ beef2k,你应该有一个void*的第一个参数.如果要为B*重载delete运算符,则必须将其作为成员编写.你不能只把第一个参数作为B*:)最好的是,只需写一个"void operator delete(void*p,size_t s)"作为成员.编译器将调用它来释放大小.你可以清除那么多字节. (3认同)
  • 尺寸并不总是与尺寸(B)相同.如果从B派生类,则编译器将调用该成员运算符delete,在这种情况下,内存的大小为sizeof(Derived)但不是sizeof(B).您可以将其设为模板:template <typename T> struct ZeroAllocated {void operator delete(void*p,size_t s){...}}; (另外,为了保持一致性,也考虑重载op new).然后结构B:ZeroAllocated <B> {....}; 我希望这是有道理的 :) (2认同)