删除在C ++中从void转换的指针是否安全？

Question

Say I've got something like that in a public header:

class MyClass
{
public:
    MyClass();

protected:
    virtual ~MyClass();

private:
    void *pSomeInternalClass;
}

And here's my implementation:

MyClass::MyClass()
{
    pSomeInteralClass = (void *) new SomeInternalClass();
}

MyClass::~MyClass()
{
    SomeInternalClass *pTemp = (SomeInternalClass *) pSomeInternalClass;
    delete pTemp;
    pSomeInternalClass = NULL;
}

The idea behind the void pointer is that I dont't have to include the definitions for the internal class in the public headers.

My question is: am I handling the void pointer in a safe way? Is there any problem with its deletion?

Thanks!

Answer 1

It's safe as long as you cast it back to it's original type.

But you don't need to do that. Just forward-declare your internal type in your public header, and you don't need to do this nasty cast.

class YourClass {
  ...
  private:
    class Internal;
    Internal *pInternal;
};

Answer 2

You do not need to include the definitions for the class in the public headers. ie

class SomeInternalClass ;
class MyClass 
{ 
public: 
    MyClass(); 

protected: 
    virtual ~MyClass(); 

private: 
    SomeInternalClass *pSomeInternalClass; 
}