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C# - Destructors



A destructor is a special method of a class which destructs or deletes an object and automatically executed when the object goes out of scope. An object goes out of scope when:

  • the method containing object ends.
  • the program ends.
  • a block containing local object variable ends.
  • a delete operator is called for an object.

Create Destructor

To create a destructor in C#, there are certain rules which need to be followed:

  • Destructor should begin with tilde sign(~) followed by class name.
  • A class can have only one destructor.
  • Unlike constructors that can have parameters, destructors do not allow any parameter.
  • Destructor do not have any return type, just like constructors.
  • When a destructor is not specified in a class, compiler generates a default destructor and inserts it into the code.

Syntax

//Creating class destructor
~className() {
  statements;
}

Example:

In the example below, a class called Circle is created. A constructor and destructor are also created. The destructor prints a message before deleting the object and called automatically when a object goes out of scope (program ends in this example).

using System;

class Circle {
  //class member field
  int radius;
  //class constructor
  public Circle(int x) {
    radius = x;
  }
  //class destructor
  ~Circle() {
    Console.WriteLine("Destructor invoked.");
  }  
  //class method
  public double area() {
    return 22/7.0*radius*radius;
  }

  static void Main(string[] args) {
    Circle Cir1 = new Circle(5);
    Circle Cir2 = new Circle(10);

    Console.WriteLine(Cir1.area());
    Console.WriteLine(Cir2.area());
  }
}

The output of the above code will be:

78.5714285714286
314.285714285714
Destructor invoked.
Destructor invoked.

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