What is wrong with my code?

[LarryChen]

Here is the code,

template<class T>
class Array1D
{
public:
	Array1D(int x):_size(x)
	{
		data = new T[_size];
	}

	~Array1D()
	{
		delete[] data;
	}

	T operator[](int x)
	{
		return data[x];
	}

	T& operator[](int x)
	{
		return data[x];
	}
private:
	int _size;
	T* data;
};

template<class T>
class Array2D
{
public:
	Array2D(int row, int col):_row(row), _col(col)
	{
		pArr = new Array1D*[_row];

		for(int i=0;i<_row;++i)
			pArr[i] = new Array1D[_col];
	}

	~Array2D()
	{
		for(int i=0;i<_row;++i)
			delete[] pArr[i];

		delete[] pArr;
	}

	Array1D operator[](int x)
	{
		return *pArr[x];
	}

	Array1D& operator[](int x)
	{
		return *pArr[x];
	}
private:
	Array1D** pArr;
	int _row;
	int _col;
};

int main(){
	Array2D<int> arr(3, 4);
	arr[1][2] = 2;
 	return 0;
}

Basically, there is a compiler error "error C2556: 'Array1D &Array2D<T>:perator [](int)' : overloaded function differs only by return type from 'Array1D Array2D<T>:perator [](int)'". What does it mean? Thanks.

[laserlight]

Perhaps you wanted to declare one of the two operator[] overloads to be a const member function?

[LarryChen]

Perhaps you wanted to declare one of the two operator[] overloads to be a const member function?

Yes! That works. But this mistake is also related to the compiler error "error C2040: 'Array2D<T>:perator []' : 'Array1D<T> &(int)' differs in levels of indirection from 'Array1D<T> (int)'". How is this error related to the overloaded operator[]? Thanks.

[2kaud]

pArr = new Array1D*[_row];

		for(int i=0;i<_row;++i)
			pArr[i] = new Array1D[_col];

You haven't specified the type to use with Array1D which takes a template argument of the type to use to instantiate the Array1D class. Also note that using the array version of new calls the default constructor for the type specified which you haven't included for Array1D.

[monarch_dodra]

You *just* defined the Array1D class. Why aren't you using it in your Array2D class? Array1D<Array1D<T>*>

[Philip Nicoletti]

1) Both classes absolutely need a Copy Constructor and and copy assignment operator

2) Get Array1D debugged before trying to use it in Array2D

3) Why does Array2D have this data member:

Array1D** pArr;

It should be either:

T ** pArr;           // in which case, you would not use Array1D ... or
Array1D<T> * pArr;  // then you would use the Array1D class

4) There is probably more ...