Constructor (object-oriented programming): Difference between revisions

Revision as of 08:43, 9 December 2019

Revision as of 09:17, 9 December 2019

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A constructor resembles an [[method (computer science)|instance method]], but it differs from a method in that it has no explicit [[return type]], it is not implicitly [[inheritance (object-oriented programming)|inherited]] and it usually has different rules for scope modifiers. Constructors often have the same name as the declaring [[class (computer science)|class]]. They have the task of [[initialization (computing)|initializing]] the object's [[data member]]s and of establishing the [[Class invariant|invariant of the class]], failing if the invariant is invalid. A properly written constructor leaves the resulting [[object (computer science)|object]] in a ''valid'' state. [[Immutable object]]s must be initialized in a constructor.

[https://readrwrite.blogspot.com/2019/12/c-class-members.html Constructor] is a [https://readrwrite.blogspot.com/2019/12/c-class-members.html class member] which is used to initialize the object and it’s always come to early binding in a program means constructor will declare if we have to assign values to the class before the creation of class. It calls by the keyword ‘new’ to instantiate an Object.

Classname Obj = new constructor ( );

Most languages allow [[method overloading|overloading]] the constructor in that there can be more than one constructor for a class, with differing parameters. Some languages take consideration of some special types of constructors. Constructors, which concretely use a single class to create objects and return a new instance of the class, are abstracted by [[Factory (object-oriented programming)|factories]], which also create objects but can do so in various ways, using multiple classes or different allocation schemes such as an [[object pool]].