C# Language Specification - Willy .Net

Chapter 17 Classesclass A{int x, y, count;}end example]public A() {x = 1;y = -1;object();count = 0;}public A(int n) {x = 1;y = -1;object();count = n;}class B: A{double sqrt2;ArrayList items;int max;public B(): this(100) {B(100);items.Add("default");}public B(int n): base(n – 1) {sqrt2 = Math.Sqrt(2.0);items = new ArrayList(100);A(n – 1);max = n;}}// Variable initializer// Variable initializer// Invoke object() constructor// Variable initializer// Variable initializer// Invoke object() constructor// Invoke B(int) constructor// Variable initializer// Variable initializer// Invoke A(int) constructor17.10.4 Default constructorsIf a class contains no instance constructor declarations, a default instance constructor is automatically provided.That default constructor simply invokes the parameterless constructor of the direct base class. If the direct baseclass does not have an accessible parameterless instance constructor, a compile-time error occurs. If the class isabstract then the declared accessibility for the default constructor is protected. Otherwise, the declaredaccessibility for the default constructor is public. [Note: Thus, the default constructor is always of the formorprotected C(): base() {}public C(): base() {}where C is the name of the class. end note][Example: In the exampleclass Message{object sender;string text;}a default constructor is provided because the class contains no instance constructor declarations. Thus, theexample is precisely equivalent toclass Message{object sender;string text;261