Can I use `abstract` keyword in C++ class

Question

Can we write abstract keyword in C++ class?

Answer 1

As others point out, if you add a pure virtual function, the class becomes abstract.

However, if you want to implement an abstract base class with no pure virtual members, I find it useful to make the constructor protected. This way, you force the user to subclass the ABC to use it.

Example:

class Base
{
protected:
    Base()
    {
    }

public:
    void foo()
    {
    }

    void bar()
    {
    }
};

class Child : public Base
{
public:
    Child()
    {
    }
};