Question: Is Default Constructor Necessary?

Is default constructor mandatory in C++?

Compiler defined default constructor is required to do certain initialization of class internals.

It will not touch the data members or plain old data types (aggregates like an array, structures, etc…).

However, the compiler generates code for default constructor based on the situation..

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

7. What happens if a user forgets to define a constructor inside a class? Explanation: The C++ compiler always provides a default constructor if one forgets to define a constructor inside a class.

Can a constructor be empty?

Empty constructor just gives you an instance of that object. … If you want to make sure that any instance created is always valid and any member variables are always initialized,then you would define the constructor which initializes all the required member variables.

What happens if you don’t declare a default constructor?

When you do not explicitly write a no-argument constructor for a class, the compiler won’t complain as long as objects are built without parameter constructors. (since compiler allows default constructor to create objects, which itself gives call to no-argument constructor).

Does every class need a default constructor C++?

Answer: C++ Empty constructor necessity depends upon class design requirements. We know that C++ class constructor is called when we create an object of a class. If a class is not required to initialize its data member or does not contain data member, there is no need to write empty constructor explicitly.

What is the purpose of a default constructor?

If not Java compiler provides a no-argument, default constructor on your behalf. This is a constructor initializes the variables of the class with their respective default values (i.e. null for objects, 0.0 for float and double, false for boolean, 0 for byte, short, int and, long).

Can constructor be overloaded?

Yes! Java supports constructor overloading. In constructor loading, we create multiple constructors with the same name but with different parameters types or with different no of parameters.

Can you have 2 constructors in Java?

There can be multiple constructors in a class. However, the parameter list of the constructors should not be same. This is known as constructor overloading.

What is the drawback of default constructor?

The drawback of a default constructor is that every instance of the class will be initialized to the same values and it is not possible to initialize each instance of the class to different values. The default constructor initializes: All numeric fields in the class to zero. All string and object fields to null.

Can we have a constructor with all default arguments?

Like all functions, a constructor can have default arguments. They are used to initialize member objects. … Note that if a constructor has any arguments that do not have default values, it is not a default constructor. The following example defines a class with one constructor and two default constructors.

Can you make a constructor 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.

How many arguments does a default constructor have?

There are two type of constructor in Java: No-argument constructor: A constructor that has no parameter is known as default constructor. If we don’t define a constructor in a class, then compiler creates default constructor(with no arguments) for the class.

Why do we create constructors in Java?

The purpose of constructor is to initialize the object of a class while the purpose of a method is to perform a task by executing java code. Constructors cannot be abstract, final, static and synchronised while methods can be. Constructors do not have return types while methods do.

How many times constructor is called?

How many times can a constructor be called during lifetime of the object? As many times as we call it. Only once.

Is constructor public by default?

Implicitly-declared default constructor If no user-declared constructors of any kind are provided for a class type (struct, class, or union), the compiler will always declare a default constructor as an inline public member of its class.