Base constructor in C# - Which gets called first? [duplicate]

Answer 1

The base constructor will be called first, otherwise, in cases where your "other stuff" must make use of member variables initialized by your base constructor, you'll get compile time errors because your class members will not have been initialized yet.

Answer 2

Constructor calls are called (fired) from the bottom up, and executed from the top down. Thus, if you had Class C which inherits from Class B which inherits from Class A, when you create an instance of class C the constructor for C is called, which in turn calls the instructor for B, which again in turn calls the constructor for A. Now the constructor for A is executed, then the constructor for B is executed, then the constructor for C is executed.

Answer 3

Actually, the derived class constructor is executed first, but the C# compiler inserts a call to the base class constructor as first statement of the derived constructor.

So: the derived is executed first, but it "looks like" the base was executed first.

Answer 4

Eric Lippert had an interesting post on the related issue of object initialization, which explains the reason for the ordering of constructors and field initializers:

Why Do Initializers Run In The Opposite Order As Constructors? Part One
Why Do Initializers Run In The Opposite Order As Constructors? Part Two

Answer 5

The base constructor will be called first.

try it:

public class MyBase
{
  public MyBase()
  {
    Console.WriteLine("MyBase");
  }
}

public class MyDerived : MyBase
{
  public MyDerived():base()
  {
    Console.WriteLine("MyDerived");
  }
}

Answer 6

As others have said, the base constructor gets called first. However, constructors are not really the first thing that happens.

Let's say you have classes like this:

class A {}

class B : A {}

class C : B {}

First, field initializers will be called in order of most-derived to least-derived classes. So first field initializers of C, then B, then A.

The constructors will then be called in the opposite order: First A's constructor, then B, then C.