Can a Derived Class Override a Virtual Function with a Different Return Type in C ?

Virtual Function Return Type in C

Question:

Can an inherited class implement a virtual function with a different return type without using a template as return?

Answer:

In certain cases, yes. It is permissible for a derived class to override a virtual function with a different return type, provided that the return type is covariant with the original return type. Covariance means that the return type of the derived function is a subtype of the return type of the base function.

Consider the following example:

class Base {
public:
    virtual ~Base() {}

    virtual Base* clone() const = 0;
};

class Derived: public Base {
public:
    virtual Derived* clone() const {
        return new Derived(*this);
    }
};

In this example, the Base class defines a pure virtual function named clone that returns a Base*. The Derived class overrides this virtual function and returns a Derived*. Even though the return type is different from the base class, this is valid because Derived* is a subtype of Base*.

In general, the return type of a function is not considered part of its signature. As long as the return type is covariant, you can override a member function with any return type.

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