c++ error: no matching function for all to

Question

I'm trying to implement a function which return a class object using its constructor. that class object as only constructor with parameters and there isnt any default constructor (cuz i dont need it). when I try to return that class object - that error comes up..

Base.cpp

Derived Base::operator+ (){ return Derived(*this); // no matching function for call to ‘Derived::Derived(Derived)’ }

Base.h

virtual Derived operator+ ();

Derived.h //Constructors:

Derived(Base &b);

Derived(Derived &d);

1. what can I do in order to fix that error?

2. whats the diffrence between declaration (const Derived &) and (Derived &)?

Thanks

How does Base can see your Derived class? I assume Derived derives from Base. — marcinj
– marcinj, Commented Jan 15, 2015 at 8:53

MSalters · Accepted Answer · 2015-01-15 08:51:12Z

1

Derived& will not bind to a temporary object. Your operator+ returns a temporary.

Solution: add const because const& will bind to temporaries.

answered Jan 15, 2015 at 8:51

MSalters

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4 Comments

michal_h Over a year ago

add const to both constructors?

michal_h Over a year ago

if I add const to the constructor, I need to change the member of the constructor to const. the problem is that if so, I cannot change that object with assignment operator which I need to implement

MSalters Over a year ago

@michal_h: No, you add const to the source object of the copy contructor. That does not affect the members, because in a copy constructor and in the assignment operator you only write to the members of the destination object.

michal_h Over a year ago

when i write: Derived::Derived(const Derived & other){ m_d=other; } its says: uninitialized reference member 'Derived'

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