This keyword is used in constructors (in constructor initializers). A derived class constructor is required to call the constructor from its base class.
In a C# program, when the default constructor isn't present, the custom base constructor can (with base) be referenced. This can eliminate duplicated code.
class exampleThe program uses a base class and a derived class. Both of the classes use a non-default, parameterful constructor.
class must use a base constructor initializer, with the base keyword, in its constructor declaration.Class A and class B have constructors. Class A is the parent or base class for class B, which is referred to as the derived class.class B derives from class A. We use a colon character to indicate inheritance.class B calls into the constructor of class A using base initializer syntax.using System;
public class A // This is the base class.
{
public A(int value)
{
// Executes some code in the constructor.
Console.WriteLine("Base constructor A()");
}
}
public class B : A // This class derives from the previous class.
{
public B(int value)
: base(value)
{
// The base constructor is called first.
// ... Then this code is executed.
Console.WriteLine("Derived constructor B()");
}
}
class Program
{
static void Main()
{
// Create a new instance of class A, which is the base class.
// ... Then create an instance of B.
// ... B executes the base constructor.
A a = new A(0);
B b = new B(1);
}
}Base constructor A()
Base constructor A()
Derived constructor B()Let us compare base and this. In a derived class, the base and this keywords can reference members. These keywords eliminate confusion as to which member we want.
class, we can use a "base" expression to directly access the base class.using System;
class Net
{
public int _value = 6;
}
class Perl : Net
{
public new int _value = 7;
public void Write()
{
// Show difference between base and this.
Console.WriteLine(base._value);
Console.WriteLine(this._value);
}
}
class Program
{
static void Main()
{
Perl perl = new Perl();
perl.Write();
}
}6
7We use these keywords to resolve ambiguous things. If the base and this keywords were removed, the compiler would not know the difference between _value fields.
class hierarchy. With them, we access members from a targeted class.There is another keyword that can be used in a constructor initializer. You can use this() with the argument list of another constructor declaration in the same type.
class, not the parent class.The base initializer is similar to the this-initializer in constructors. We can specify the base initializer when deriving from types with non-default constructors.