Class instances differences

Posted by krrishbiju-15589 under C# on 7/25/2013 | Points: 10 | Views : 986 | Status : [Member] | Replies : 6

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Hi ,
I have class ClassA.
What is the difference between
ClassA ob=new ClassA(); and
ClassA ob=null;

Thanks and Regards
krrish

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Posted by: Satyapriyanayak on: 7/25/2013 [Member] [MVP] Silver | Points: 25

0	In C#, the new keyword can be used as an operator or as a modifier. new Operator The new operator is used to create objects and invoke constructors, for example: Class1 MyClass = new Class1(); The null keyword is a literal that represents a null reference, one that does not refer to any object. null is the default value of reference-type variables. Ordinary value types cannot be null. However, C# 2.0 introduced nullable value types http://msdn.microsoft.com/en-us/library/51y09td4%28v=vs.71%29.aspx http://msdn.microsoft.com/en-us/library/edakx9da.aspx If this post helps you mark it as answer Thanks krrishbiju-15589, if this helps please login to Mark As Answer. \| Alert Moderator

In C#, the new keyword can be used as an operator or as a modifier.
new Operator

The new operator is used to create objects and invoke constructors, for example:

Class1 MyClass = new Class1();

The null keyword is a literal that represents a null reference, one that does not refer to any object. null is the default value of reference-type variables. Ordinary value types cannot be null. However, C# 2.0 introduced nullable value types

http://msdn.microsoft.com/en-us/library/51y09td4%28v=vs.71%29.aspx

http://msdn.microsoft.com/en-us/library/edakx9da.aspx

If this post helps you mark it as answer
Thanks

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Posted by: Ssj_Kumar on: 7/25/2013 [Member] Starter | Points: 25

0	Adding some more interesting points Class1 MyClass=new Class1(); Memory will be created in Heap This is reference type Class1 MyClass=null; Memory will be created in Stack This is Value type Regards, Jayakumar Selvakani krrishbiju-15589, if this helps please login to Mark As Answer. \| Alert Moderator

Posted by: krrishbiju-15589 on: 7/25/2013 [Member] Starter | Points: 25

0	Interesting....can you pleases explain when and why these two used..... Thanks krrish krrishbiju-15589, if this helps please login to Mark As Answer. \| Alert Moderator

Posted by: Ssj_Kumar on: 7/27/2013 [Member] Starter | Points: 25

0	Have a look on below link, it may explain some extend http://forums.asp.net/t/1906391.aspx/1?difference+between+class+variable+and+class+object+c+ Regards, Jayakumar Selvakani krrishbiju-15589, if this helps please login to Mark As Answer. \| Alert Moderator

Posted by: aswinialuri-19361 on: 7/30/2013 [Member] Starter | Points: 25

0	hi, ClassA ob=new ClassA(); it creates new instance and default constructor ClassA ob=null; it is null reference and it doesn't create any constructor. Mark as Answer if it helps you Thanks&Regards Aswini Aluri krrishbiju-15589, if this helps please login to Mark As Answer. \| Alert Moderator

Posted by: Ssj_Kumar on: 7/31/2013 [Member] Starter | Points: 25

0	Class1 MyClass=new Class() Object will be created in Heap and address will be saved in Stack, In this case we are using both Heap and StacK In this case this is reference type Class1 MyClass=null; Object will not be created so it won't create your Heap, Only Stack memory will be created and it hold Null Value In this case this is Value type Regards, Jayakumar Selvakani krrishbiju-15589, if this helps please login to Mark As Answer. \| Alert Moderator

Class1 MyClass=new Class()
Object will be created in Heap and address will be saved in Stack, In this case we are using both Heap and StacK
In this case this is reference type

Class1 MyClass=null;
Object will not be created so it won't create your Heap, Only Stack memory will be created and it hold Null Value
In this case this is Value type

Regards,
Jayakumar Selvakani

krrishbiju-15589, if this helps please login to Mark As Answer. | Alert Moderator

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