CODEWITHSUNDEEP
c++inheritance
gibraltar
gibraltar

Reputation: 1708

C++ inherited operator not being called in the derived class

I have following code in C++

#include <iostream>
#include <list>
#include <algorithm>

using namespace std;

class A{
  public:
    int x;
    int y;
    int first(){
      return x;
    }
    int second(){
      return y;
    }
};

class C{
  public:
    float a,b;
    C(){
      a = 0.0f;
      b = 0.0f;
    }
    template<class T>
      C(T t){
        cout<<"Copy Constructor\n";
        a = t.first();
        b = t.second();
      }
      template<class T>
    C & operator=(T const &c){
        cout <<"Assignment operator\n";
        this->a = c.first();
        this->b = c.first();
    }
};

class D: public C{
  public:
    template <typename T> D (T t) : C(t) {}
    float area(){
      return a*b; 
    }
};

int main(){
  A a;
  a.x = 6;
  a.y = 8;
  C c(a);
  D d(a);
  D e = a;   // Here copy constructor is being called!!
  cout<<e.a<<" "<<e.b<<" "<<e.area()<<endl;
}

Here is the output of the above program

Copy Constructor
Copy Constructor
Copy Constructor
6 8 48

Why is assignment operator not being called in derived class?

Edit1 : I have changed the question to make the question more clear.

Upvotes: 0

Views: 202

Answers (2)

Joel Falcou
Joel Falcou

Reputation: 6357

You can grab back said operator= explicitly using :

using C::operator=

in D class.

operator= are inherited but masked by default by th eone generated by th ecompiler.

Upvotes: 0

Antonio P&#233;rez
Antonio P&#233;rez

Reputation: 7002

Constructors are not inherited as regular public functions. Default constructor are defined by the compiler if missing, but you should define a constructor taking an A parameter (or templated as you did for C) for D. You will need an assignment operator to be defined as well.

class D: public C{
  public:
    D(A aparam)
    : a(aparam.first(), b(aparam.second()){
    }
    D& operator=(const D& rhs){
      a = rhs.first();
      b = rhs.second();
    }
    float area(){
      return a*b; 
    }
};

Upvotes: 2

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