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

Question

Can we write abstract keyword in C++ class?

Answer 1

There is no keyword 'abstract' but a pure virtual function turns a class in to abstract class which one can extend and re use as an interface.

Answer 2

#define abstract

Answer 3

No, C++ has no keyword abstract. However, you can write pure virtual functions; that's the C++ way of expressing abstract classes. It is a keyword introduced as part of the C++/CLI language spefication for the .NET framework. You need to have at least one pure virtual function in a class to be abstract.

class SomeClass {
public:
   virtual void pure_virtual() = 0;  // a pure virtual function
};

Answer 4

No, you can't use abstract as a keyword because there is no such keyword available in C++.

If you want make a class as an in C++ abstract you can declare at least one function as pure virtual function.

But in derived class you must provide definition else its give compilation error .

Example:

class A
{
public:
  virtual void sum () = 0;
};

note:

You can used abstract as a variable name, class name because, as I told you, abstract is not a keyword in C++.