Why Compiler do not provide default assignment operator if a class has non-static data membera of const or referance type in C++?

Question

#include<iostream> 
using namespace std; 

class Test     
{ 
    int x; 
    int &ref; 
public: 
    Test (int i):x(i), ref(x) {} 
    void print() { cout << ref; } 
    void setX(int i) { x = i; }     
}; 

int main()     
{     
    Test t1(10);     
    Test t2(20);     
    t2 = t1;     
    t1.setX(40);     
    t2.print();     
    return 0;     
}

This program gives an compiler error

All this program gives *me* is sore eyes. Please take the time to format your question, and add the complete error message. — Quentin, Oct 18 '19 at 13:16
Try to write this operator yourself. You will see that it's impossible, which should be good enough reason for not expecting the compiler to do it. — Max Langhof, Oct 18 '19 at 13:21
It's a duplicate of https://stackoverflow.com/q/10781130/11631696 — h4ckthepl4net, Oct 18 '19 at 13:27

score 0 · Answer 1 · answered Oct 18 '19 at 13:29

0

References and const variables can only be given a value at construction time. The assignment operator only works on objects that are already constructed.

answered Oct 18 '19 at 13:29

Mark Ransom

299,747
42
398
622

Here object will construct before only then how it would give error? – user12238659 Oct 18 '19 at 16:51
@user12238659 once the object is constructed, those references and const values can't be changed. The default assignment operator requires the values of all members to be copied, i.e. changed. – Mark Ransom Oct 18 '19 at 17:32

Why Compiler do not provide default assignment operator if a class has non-static data membera of const or referance type in C++?

1 Answers1