Template with Two Types Confusion C++ - c++

Question

I'm trying to make a simple template of creating an array class. However, I want to use two arguments: one typename and one int variable. I'm running into two errors and I'm not sure what I'm doing wrong. Here is my source which is simple and works.
int main()
{
Array<int, 7> tArray;
std::cout << tArray.getSize() << std::endl;
for (int i = 0; i < tArray.getSize(); i++)
{
tArray.insert(i + 5);
i++;
}
tArray.printArray();
return 0;
}
The error/issue I'm having is regarding two functions in my header file.
#pragma once
template <typename T, int S>
class Array
{
private:
T arr[S];
public:
Array();
int getSize() const;
int insert(T val);
void printArray();
~Array();
};
cArray<T, S>::cArray() { }
template <typename T, int S>
int Array<T, S>::insert(T val)
{
Array<T, S>* temp = new Array[S];
temp = this;
return temp[val];
}
template <typename T, int S>
void Array<T, S>::printArray()
{
Array<T, S>* temp = new Array[S];
temp = this;
for (int i = 0; i < S; i++)
{
std::cout << tempArray[i] << std::endl;
}
}
The functions insert and printArray are not working. For the insert function, the error being returned states: Suppression State Error C2440 'return': cannot convert from 'Array<int,7>' to 'int'
The printArray is displaying nothing.
This is the first time I'm using a template with two arguments so I'm a bit confused on what I'm doing wrong here. Any takes?

Answer 1

The offending code is here:
template <typename T, int S>
int Array<T, S>::insert(T val) {
Array<T, S>* temp = new Array[S];
temp = this;
return temp[val];
}
First, you create an array of Arrays, because you wrote an expression that looks like:
Type *var = new Type[count];
Then you change the pointer to that array to this. Then you try to return the element at index val of the array temp, and this element has type Array<T, S>. But, the return type is int, so, that is why the compiler complains that it cannot convert Array<int, 7> to int.
You should not use new here at all. You already have allocated memory for the array (it's the member variable arr), you just need to copy val into the right place in that array. To do that, you need to keep track of how many elements you already inserted in the array. (Note that S is a constant that just says what the maximum amount of elements is you can store.) So:
template <typename T, int S>
class Array {
T arr[S];
size_t size = 0;
...
};
template <typename T, int S>
void Array<T, S>::insert(T val)
{
arr[size++] = val;
}
template <typename T, int S>
size_t Array<T, S>::getSize()
{
return size;
}
And printArray() has similar issues. You should print the contents of arr, you should not create a new temporary array and try to print its elements.