Having such a class without a constructor is fine. Constructors are generally required if need either an assignment operator or destructor. This isn't so much a compiler enforced rule as a general design issue.
Is it mandatory to use the construtors in a class?
As to being mandatory, that really depends on the programming language; in the case of Java, each class must have a constructor, however, in many cases Java will automatically provide a default constructor, so you don't really need to program it. Is it mandatory to use the construtors in a class in c plus plus?
Is it mandatory to have a constructor in Java?
Yes, by definition both in C++ and Java, a constructor is a method which has the name same as the class name, and therefore it is mandatory, as the compiler / JVM will not consider it as a constructor. What happens if the constructor of a class A is made private?
Do all classes have constructors by default?
All classes have constructors by default: if you do not create a class constructor yourself, C# creates one for you. However, then you are not able to set initial values for fields. Constructors save time! Take a look at the last example on this page to really understand why.
Why do we need constructors in C++?
All a constructor is intended to do for you is put your class object "in a good state." That means that nothing your class object contains, if used, could lead to undefined behavior-- like uninitialized pointers. But although C++ gives you enough bullets to shoot yourself in the foot this way, I like to think those bullets could be "useful".
What happens if we don't use constructor for a class?
If we don't define a constructor in a class, then the compiler creates a default constructor(with no arguments) for the class.
Is it mandatory to use a constructor in a class in C Plus Plus?
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 happens if you do not provide any constructor to a class in C?
If no constructors are declared in a class, the compiler provides an implicit inline default constructor. If you rely on an implicit default constructor, be sure to initialize members in the class definition, as shown in the previous example.
Is it necessary to create constructor?
The compiler provides it if you don't write any constructors for your class. The default constructor accepts no parameters and, if your class is a subclass, calls the zero-parameters constructor on the superclass.
Is it mandatory to use constructors in a class?
Users do not need to write constructors for every class. A constructor can be declared using any of the access modifiers. It is mandatory to have a constructor with the right access modifier. However, the compiler supplies a default if an access modifier is not defined in the class and a constructor is not declared.
How many constructor can a class have?
You can have 65535 constructors in a class(According to Oracle docs).
Can a class have no constructor?
Java doesn't require a constructor when we create a class. However, it's important to know what happens under the hood when no constructors are explicitly defined. The compiler automatically provides a public no-argument constructor for any class without constructors. This is called the default constructor.
What is the role of a constructor in classes?
1. What is the role of a constructor in classes? Explanation: A constructor is used in classes to initialize data members of class in order to avoid errors/segmentation faults.
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 is constructor important?
Importance of constructors Constructors are used to initialize the objects of the class with initial values. Constructors are invoked automatically when the objects are created. Constructors can have default parameters. If constructor is not declared for a class , the C++ compiler generates a default constructor.
What is the benefit of using constructor?
One of the benefits of using a constructor over a method is that you can be assured the constructor was called and the work within the constructor was performed. The language specifies that to construct an object a constructor must be called.
Why do we need a default constructor?
What is the significance of the default constructor? They are used to create objects, which do not have any having specific initial value. Is a default constructor automatically provided? If no constructors are explicitly declared in the class, a default constructor is provided automatically.
What is the use of constructor in C++?
A constructor in C++ is a special 'MEMBER FUNCTION' having the same name as that of its class which is used to initialize some valid values to the data members of an object. It is executed automatically whenever an object of a class is created.
Why do we write constructor in C++?
The main purpose of the class constructor in C++ programming is to construct an object of the class. In other word, it is used to initialize all class data members. For example, in below class, constructor Car () is initializing data members with default values.
What is the role of a constructor in classes?
1. What is the role of a constructor in classes? Explanation: A constructor is used in classes to initialize data members of class in order to avoid errors/segmentation faults.
What are the rules of constructor in C++?
The rules for writing a constructor functions areThey should be declared in the public section.They are invoked automatically when the objects are created.They should not have return types, therefore they cannot return values.They cannot be inherited.They can have default arguments.Cannot refer to addresses.More items...•
Why are classes without constructors given a constructor in C#?
Unless the class is static, classes without constructors are given a public parameterless constructor by the C# compiler in order to enable class instantiation. For more information, see Static Classes and Static Class Members.
What does it mean when a base class does not have a constructor?
If a base class does not offer a parameterless constructor, the derived class must make an explicit call to a base constructor by using base . A constructor can invoke another constructor in the same object by using the this keyword.
What is a constructor that takes no parameters called?
A constructor that takes no parameters is called a parameterless constructor . Parameterless constructors are invoked whenever an object is instantiated by using the new operator and no arguments are provided to new. For more information, see Instance Constructors.
What is the name of the class or struct that initializes the data?
When a class or struct is created, its constructor is called. Constructors have the same name as the class or struct, and they usually initialize the data members of the new object.
How to declare a constructor static?
A constructor can be declared static by using the static keyword. Static constructors are called automatically, immediately before any static fields are accessed, and are generally used to initialize static class members. For more information, see Static Constructors.
Can constructors be public?
Constructors can be marked as public, private, protected, internal, protected internal or private protected. These access modifiers define how users of the class can construct the class. For more information, see Access Modifiers. A constructor can be declared static by using the static keyword.
Can a constructor be used as a parameter?
Any parameters to the constructor can be used as parameters to base, or as part of an expression. For more information, see base. In a derived class, if a base-class constructor is not called explicitly by using the base keyword, the parameterless constructor, if there is one, is called implicitly.
What is a constructor in C++?
Constructors in C++. What is constructor? A constructor is a special type of member function of a class which initializes objects of a class. In C++, Constructor is automatically called when object (instance of class) create.
Why is a constructor a special member function?
It is special member function of the class because it does not have any return type. How constructors are different from a normal member function? A constructor is different from normal functions in following ways: Constructor has same name as the class itself. Constructors don’t have return type.
How to create a parameterized constructor?
To create a parameterized constructor, simply add parameters to it the way you would to any other function. When you define the constructor’s body, use the parameters to initialize the object .
When an object is declared in a parameterized constructor, the initial values have to be passed as arguments to the
When an object is declared in a parameterized constructor, the initial values have to be passed as arguments to the constructor function. The normal way of object declaration may not work. The constructors can be called explicitly or implicitly.
Do constructors have return type?
Constructors don’t have return type. A constructor is automatically called when an object is created. It must be placed in public section of class. If we do not specify a constructor, C++ compiler generates a default constructor for object (expects no parameters and has an empty body). Let us understand the types of constructors in C++ by taking ...
What is a constructor in a class?
A constructor is a special method that is used to initialize objects. The advantage of a constructor, is that it is called when an object of a class is created. It can be used to set initial values for fields:
Does a constructor have to match the class name?
Note that the constructor name must match the class name, and it cannot have a return type (like void or int ). Also note that the constructor is called when the object is created. All classes have constructors by default: if you do not create a class constructor yourself, C# creates one for you.
