Sequence of constructor call

Abhineet Srivastava

Suppose we have class-Class A & Class B

Class A Have one Default Constructor & One Paramatrized constructor

Class B Have one Default Constructor & One Paramatrized constructor

If we create the Object of B...What will be the sequence of constructor call..

Kindly Tell Me..

Thanks!!

10 Replies

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Abhineet Srivastava13y ago
OK..

Got it..

Thank you very much!!
Vulpes13y ago
In that case, it simply won't compile,. The error you'll get is:

Cannot implicitly convert type 'B' to 'A'
Abhineet Srivastava13y ago
No Vupas...

I m saying that what will happen when b Don't inherit class A & We are creating objest like

A a =new B();
Vulpes13y ago
If the code is like this:

using System;

class A
{
public A()
{
Console.WriteLine("Hi");
}
}

class B : A
{
public B()
{
Console.WriteLine("Bye");
}
}

class Test
{
static void Main()
{
A a = new B();
}
}

then the output will be:

Hi
Bye

As before A's constructor will run first, followed by B's constructor.

The fact that you're creating an object of type B and assigning a reference to it to a variable of type A makes no difference to the constructor logic.
Abhineet Srivastava13y ago
one more question to clear vulps-
suppose our code is like that-

Class a
{
C.w("Hi")
}
class B
{
c.w("Bye")
}

Class Test
{
A a = New B();
}

Then what will output?
Abhineet Srivastava13y ago
Thanks Mate :)

Now,Its has been clear for me
Vulpes13y ago
Here's some example code which illustrates my previous reply:

using System;

class A
{
public A()
{
Console.WriteLine("A's default constructor called");
}

public A(int i)
{
Console.WriteLine("A's parameterized constructor called - {0} passed", i);
}
}

class B : A
{
public B()
{
Console.WriteLine("B's default constructor called");
}

public B(int i) : base(i)
{
Console.WriteLine("B's parameterized constructor called - {0} passed", i);
}
}

class Test
{
static void Main()
{
B b = new B();
Console.WriteLine();
B b2 = new B(3);
Console.ReadKey();
}
}

The output is:

A's default constructor called
B's default constructor called

A's parameterized constructor called - 3 passed
B's parameterized constructor called - 3 passed
Vulpes13y ago
The code within the constructors will execute in the following order:

System.Object's default constructor (does nothing).

A's constructor. This will be the default constructor unless the parameterized one is specified using the 'base' keyword.

B's default constructor if no arguments are specified when creating the B object, otherwise B's parameterized constructor.
Abhineet Srivastava13y ago
Class B inherit Class A
Prashant Yadav13y ago
What is the relationship between Class A and Class B ? Create one console app do onsole write in constructor and see your self