freeing a void pointer

Question

How to free a void pointer.

struct vStruct {
    void *vPtr;
    struct vStruct *next;
};

struct vStruct sObj;
struct vStruct *sObjNew = sObj;

delete sObjNew-&         


        

Answer 1

You should not delete a void pointer. delete works for specific types (such that compiler knows, which destructor should be called - as stated in error message).

If you want to hold unspecified type in your structure, you have to wrap it somehow.

class DataWrapper
{
public:
    virtual void * GetData() = 0;            
    virtual ~DataWrapper()
    {
    }
};

class MyDataWrapper
{
protected:
    MyData * data;

public:
    MyDataWrapper(MyData * newData)
    {
        data = newData;
    }

    void * GetData()
    {
        return data;
    }

    ~MyDataWrapper()
    {
        delete data;
    }
};

struct vStruct
{
    MyDataWrapper * vPtr;
    struct vStruct *next;

    ~vStruct()
    {
        if (vPtr != null)
            delete vPtr;
    }
};

vStruct sObj;
sObj.vPtr = new MyDataWrapper(new MyData());

// When sObj gets deleted, MyDataWrapper is
// deleted too (thanks to the ~vStruct) and
// in effect, the allocated data is deleted too.

Note, that it's a simple example, it can be written more aesthetically.