Assigning objects of class

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1.00/5 (1 vote)

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C#

class A
{
}
class B :A
{
}
class Prog
{
Static void main()
{
A a=new A();
B b=new B();
a=b;
b=a;
}
}

can we assign the objects like dis.

Posted 14-Dec-12 20:07pm

chetan.sn

Updated 14-Dec-12 20:10pm

Krunal Rohit

v2

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[no name] 15-Dec-12 2:11am

What your are up to ?

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Sergey Alexandrovich Kryukov · Answer 1 · 2012-12-14T20:29:00

Yes, you can, but you need to understand clearly what happens. No new object is created by such assignment.

As the type is class, which is a reference type, you end up having two different references to the same object, which is, of course, often needed. A new object is only created with a constructor. Even if there is no constructors, and the object is created using some factory method, internally it is still created via a constructor, with heap memory allocation.

You need to read on value and reference types.

Good luck,

—SA

wmdroshan · Answer 2 · 2012-12-14T21:20:00

Hi,

According to your code I don't think it is possible. It is not possible because Visual Studio will give a compile error at b=a;. The reason is A is the parent class and the B is the child class. So compiler works according to the rule of 'No parent object can assigned to a child object". But vice-verse is possible. But you can overcome this compile error by casting as,

b = (B)a;

For this scenario this works because at the previous line you have assigned as

a = b

These classes are reference types, so after

a = b

'a' is actually a B class instance. If you remove the

a = b

then a run time exception will be throwed as

System.InvalidCastException

with the message

Unable to cast object of type 'A' to type 'B'

Regards.

Assigning objects of class

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