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Understand how C++ templates ensure safe type conversions by using std::is_convertible to check type compatibility. This lesson demonstrates copying data between arrays of different types and highlights potential errors when types are incompatible, helping you write safer, more flexible template code.

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Solution Review #

C++
// templateClassTemplateMethods.cpp
#include <type_traits>
#include <algorithm>
#include <iostream>
#include <vector>
template <typename T, int N>
class Array{
public:
  Array()= default;
  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;
  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;
  Array<std::string, 10> strArray{};
  Array<int, 100> bigIntArray{};
  // doubleArray= strArray;            // ERROR: cannot convert ‘const std::basic_string<char>’ to ‘double’
  // doubleArray= bigIntArray;         // ERROR: no match for ‘operator=’ in ‘doubleArray = bigIntArray
}

Explanation

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