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Generic Programming Templates in C++

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Explore how C++ templates treat classes instantiated with different arguments as distinct types. Understand why the Array template class must declare itself as a friend to access private members across template instances. This lesson clarifies template instantiation nuances and class template friendship for copying array contents securely and efficiently.

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Solution Review

C++
//templateClassTemplateMethods2.cpp
#include <algorithm>
#include <iostream>
#include <vector>
template <typename T, int N>
class Array{
public:
  Array()= default;
  
  template <typename T2, int M> friend class Array;  
  template <typename T2>
  Array<T, N>& operator=(const Array<T2, N>& arr){
	  static_assert(std::is_convertible<T2, T>::value, "Cannot convert source type to destination type!");
    elem.clear();
	  elem.insert(elem.begin(), arr.elem.begin(), arr.elem.end());
	  return *this;
  }
  int getSize() const;
private:
  
  std::vector<T> elem;
};
template <typename T, int N>
int Array<T, N>::getSize() const {
  return N;
}
int main(){
  Array<double, 10> doubleArray{};
  Array<int, 10> intArray{};
  doubleArray = intArray;
}
...