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Constructors

Constructors

Constructors are a feature.

In class-based object-oriented programming, a constructor (abbreviation: ctor) is a special type of subroutine called to create an object. It prepares the new object for use, often accepting arguments that the constructor uses to set required member variables.


Languages with Constructors include Java, JavaScript, Python, C++, PHP, MATLAB, C#, Objective-C, Visual Basic .NET, Object Pascal, Action!, CFML

Example from JavaScript:
class Person { constructor(name) { this._name = name } } new Person("Jane")
Example from C++:
class Foobar { public: Foobar(double r = 1.0, double alpha = 0.0) // Constructor, parameters with default values. : x_(r * cos(alpha)) // <- Initializer list { y_ = r * sin(alpha); // <- Normal assignment } private: double x_; double y_; }; Foobar a, b(3), c(5, M_PI/4);
Example from C#:
public class MyClass { private int a; private string b; // Constructor public MyClass() : this(42, "string") { } // Overloading a constructor public MyClass(int a, string b) { this.a = a; this.b = b; } } // Code somewhere // Instantiating an object with the constructor above MyClass c = new MyClass(42, "string");
Example from CFML:
component { // properties property name="cheeseName"; // constructor function Cheese init( required string cheeseName ) { variables.cheeseName = arguments.cheeseName; return this; } }
constants-feature.html 路 constructor-feature.html 路 dependent-types-feature.html

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