Question

I’m trying to cast away const from an object but it doesn’t work. But if I use old C-way of casting code compiles. So which casting I’m suppose to use to achieve this same effect? I wouldn’t like to cast the old way.

//file IntSet.h

#include "stdafx.h"
#pragma once
/*Class representing set of integers*/
template<class T>
class IntSet
{
private:
    T** myData_;
    std::size_t mySize_;
    std::size_t myIndex_;
public:
#pragma region ctor/dtor
    explicit IntSet();
    virtual ~IntSet();
#pragma endregion
#pragma region publicInterface
    IntSet makeUnion(const IntSet&)const;
    IntSet makeIntersection(const IntSet&)const;
    IntSet makeSymmetricDifference(const IntSet&)const;
    void insert(const T&);

#pragma endregion
};

//file IntSet_impl.h

#include "StdAfx.h"
#include "IntSet.h"

#pragma region ctor/dtor
template<class T>
IntSet<T>::IntSet():myData_(nullptr),
                    mySize_(0),
                    myIndex_(0)
{
}

IntSet<T>::~IntSet()
{
}
#pragma endregion

#pragma region publicInterface
template<class T>
void IntSet<T>::insert(const T& obj)
{
    /*Check if we are initialized*/
    if (mySize_ == 0)
    {
        mySize_ = 1;
        myData_ = new T*[mySize_];
    }
    /*Check if we have place to insert obj in.*/
    if (myIndex_ < mySize_)
    {//IS IT SAFE TO INCREMENT myIndex while assigning?
        myData_[myIndex_++] = &T(obj);//IF I DO IT THE OLD WAY IT WORKS
        return;
    }

    /*We didn't have enough place...*/
    T** tmp = new T*[mySize_];//for copying old to temporary basket
    std::copy(&myData_[0],&myData_[mySize_],&tmp[0]);

}
#pragma endregion

Thanks.

Answer 1

There’s a dedicated C++ casting operator for dealing with const: const_cast:

myData_[myIndex_++] = &const_cast<T>(obj);