Can Abstract Class Have Constructor C++?

What happens if a user forgets to define a constructor inside a class?

Also if any user forgets to define init() function then no object will be initialized whereas if any constructor is not defined in any class the class provides a default constructor for initialization.

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What is a copy constructor?.

Can an abstract class be instantiated?

Abstract classes cannot be instantiated, but they can be subclassed. When an abstract class is subclassed, the subclass usually provides implementations for all of the abstract methods in its parent class. However, if it does not, then the subclass must also be declared abstract .

Can an abstract class have a constructor?

Yes! Abstract classes can have constructors! Yes, when we define a class to be an Abstract Class it cannot be instantiated but that does not mean an Abstract class cannot have a constructor. Each abstract class must have a concrete subclass which will implement the abstract methods of that abstract class.

Can abstract class have body?

Abstract methods are declaration only and it will not have implementation. It will not have a method body. A Java class containing an abstract class must be declared as abstract class. An abstract method can only set a visibility modifier, one of public or protected.

Can a constructor be final?

No, a constructor can’t be made final. A final method cannot be overridden by any subclasses. … But, in inheritance sub class inherits the members of a super class except constructors. In other words, constructors cannot be inherited in Java therefore, there is no need to write final before constructors.

Can constructor be static?

A static constructor does not take access modifiers or have parameters. A class or struct can only have one static constructor. Static constructors cannot be inherited or overloaded. A static constructor cannot be called directly and is only meant to be called by the common language runtime (CLR).

Can abstract class be inherited?

An abstract class defines the identity of a class. An interface can inherit multiple interfaces but cannot inherit a class. An abstract class can inherit a class and multiple interfaces. … An abstract class can declare constructors and destructors.

Can we make abstract class as final?

In short, an abstract class cannot be final in Java, using both abstract and final modifier with a class is illegal in Java. … An abstract method must be overridden to be useful and called but when you make the abstract method final it cannot be overridden in Java, hence there would be no way to use that method.

Can an abstract class have a constructor C++?

A class with one (or more) virtual pure functions is abstract, and it can’t be used to create a new object, so it doesn’t have a constructor.

Can a constructor have a return type C++?

Constructors don’t have return type. A constructor is automatically called when an object is created. If we do not specify a constructor, C++ compiler generates a default constructor for us (expects no parameters and has an empty body).

Can an abstract class have attributes?

Can have both. If at least one method is abstract, a class is abstract.

What happens if you keep a return type for a constructor?

Since constructor can only return the object to class, it’s implicitly done by java runtime and we are not supposed to add a return type to it. If we add a return type to a constructor, then it will become a method of the class. This is the way java runtime distinguish between a normal method and a constructor.

Why does an abstract class have a constructor?

The main purpose of the constructor is to initialize the newly created object. In abstract class, we have an instance variable, abstract methods, and non-abstract methods. … The constructor inside the abstract class can only be called during constructor chaining i.e. when we create an instance of sub-classes.

Can constructor be private?

Yes, we can declare a constructor as private. If we declare a constructor as private we are not able to create an object of a class. We can use this private constructor in the Singleton Design Pattern.

Why constructor has no return type?

So the reason the constructor doesn’t return a value is because it’s not called directly by your code, it’s called by the memory allocation and object initialization code in the runtime. … The whole purpose of constructor is to initialize the current state of the object by setting the initial values.