Why are derived class fields initialized before the base class fields

Erik Movsesyan

4y836C#

I know that the following is the order of data members initialization and constructor call when creating a derived class object.

Derived static fields
Derived static constructor
Derived instance fields
Base static fields
Base static constructor
Base instance fields
Base instance constructor
Derived instance constructor

Everything here seems pretty logical except for ONE thing:
I can not understand why is that that derived class fields get initialized before base class fields? Honestly I can not find any valid and logical explanation for that after scouring the internet and giving it a lot of thought.

3 Replies

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Sachin Singh4y ago
Accepted answer
You didn't get the point.
It is not about derived or base. In the end what matters is the importance of object-oriented programing, which says everything is an Object and an object is an object because it has some well-defined attributes. A car is not an object but a Red Car is an Object.

Now, when something is already defined then, then-and-there it goes to memory as soon as the compiler reads it. Although the object goes to memory after the constructor is called but not the fields which are already initialized.

so the compiler is executing---> hits a class ---> ohh! some attributes are initialized good (create space for this in RAM)---> what? it is a child of some parent---> let's meet the parent --> Create a memory for Parent Object (by calling constructor)--> Come to child ---> Create memory for child object (by calling constructor)
Erik Movsesyan4y ago
@Sachin Singh , I agree with what you say and thank you for the reply but my question was different.
I am not asking about Constructors. I am asking Why are DERIVED class fields initialized BEFORE Base class fields.
Sachin Singh4y ago
It is not the way you are thinking but Yes, your sequencing is correct.

The compiler doesn't know anything about the base class until it finds the class he is going to instantiate is inheriting from another class so he should initialize the parent. Here, initializing just means calling the constructor and nothing else.
The constructor by default initializes the un-initialized fields (Yes mark it, un-initialized fields or the fields which are initialized by the developer in the constructor, not the already initialized fields using the field initializers.)

The main purpose of the constructor is to only initialize the members because an object is an object only because of its fields meaning a mango is a class until the compiler doesn't make it a yellow mango or mango of price zero (0). But if it has any attributes which are already initialized (compiler read it while reading the class before creating the object) there is no need for a constructor, although to make 100% sure that all fields are initialized/the developer will initialize the fields, constructors are called.