In C#, do you need to call the base constructor?
Solution 1:
You do not need to explicitly call the base constructor, it will be implicitly called.
Extend your example a little and create a Console Application and you can verify this behaviour for yourself:
using System;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
MyClass foo = new MyClass();
Console.ReadLine();
}
}
class BaseClass
{
public BaseClass()
{
Console.WriteLine("BaseClass constructor called.");
}
}
class MyClass : BaseClass
{
public MyClass()
{
Console.WriteLine("MyClass constructor called.");
}
}
}
Solution 2:
It is implied, provided it is parameterless. This is because you need to implement constructors that take values, see the code below for an example:
public class SuperClassEmptyCtor
{
public SuperClassEmptyCtor()
{
// Default Ctor
}
}
public class SubClassA : SuperClassEmptyCtor
{
// No Ctor's this is fine since we have
// a default (empty ctor in the base)
}
public class SuperClassCtor
{
public SuperClassCtor(string value)
{
// Default Ctor
}
}
public class SubClassB : SuperClassCtor
{
// This fails because we need to satisfy
// the ctor for the base class.
}
public class SubClassC : SuperClassCtor
{
public SubClassC(string value) : base(value)
{
// make it easy and pipe the params
// straight to the base!
}
}
Solution 3:
It's implied for base parameterless constructors, but it is needed for defaults in the current class:
public class BaseClass {
protected string X;
public BaseClass() {
this.X = "Foo";
}
}
public class MyClass : BaseClass
{
public MyClass()
// no ref to base needed
{
// initialise stuff
this.X = "bar";
}
public MyClass(int param1, string param2)
:this() // This is needed to hit the parameterless ..ctor
{
// this.X will be "bar"
}
public MyClass(string param1, int param2)
// :base() // can be implied
{
// this.X will be "foo"
}
}
Solution 4:
It is implied.