Difference between array, arraylist, List, Hashtable, Dictionary and SortedList in c#

-
Basic difference is that arrays are of fixed size. Whereas an ArrayList implements the list data structure and can dynamically grow. While arrays would be more performance that a list, a list would be far more flexible since you don't need to know the required size initially. Array - represents an old-school memory array - kind of like a alias for a normal type[] array. Can enumerate. Can't grow automatically. I would assume very fast insertion, retrieve and speed. ArrayList - automatically growing array. Adds more overhead. Can enum., probably slower than a normal array but still pretty fast. These are used a lot in .NET List - one of my favorites - can be used with generics, so you can have a strongly typed array, e.g. List . Other than that, acts very much like ArrayList. Hashtable - plain old hashtable. O(1) to O(n) worst case. Can enumerate the value and keys properties, and do key/val pairs. Dictionary - same as above only strongly typed via generics, such a...
Post a Comment

C# Interview questions on Boxing and Unboxing

-
What is Boxing and Unboxing?
Boxing - Converting a value type to reference type is called boxing. An example is shown below.
int i = 101;
object obj = (object)i; // Boxing

Unboxing - Converting a reference type to a value typpe is called unboxing. An example is shown below.
obj = 101;
i = (int)obj; // Unboxing

Is boxing an implicit conversion?
Yes, boxing happens implicitly.

Is unboxing an implicit conversion?
No, unboxing is an explicit conversion.

What happens during the process of boxing?
Boxing is used to store value types in the garbage-collected heap. Boxing is an implicit conversion of a value type to the type object or to any interface type implemented by this value type. Boxing a value type allocates an object instance on the heap and copies the value into the new object. Due to this boxing and unboxing can have performance impact.

Comments

Post a Comment

Popular posts from this blog

C# Interview Questions on Inheritance

-
What are the 4 pillars of any object oriented programming language? 1. Abstraction 2. Inheritance 3. Encapsulation 4. Polymorphism Do structs support inheritance? No, structs do not support inheritance, but they can implement interfaces. What is the main advantage of using inheritance? Code reuse Is the following code legal? class ChildClass : ParentClassA, ParentClassB { } No, a child class can have only one base class. You cannot specify 2 base classes at the same time. C# supports single class inheritance only. Therefore, you can specify only one base class to inherit from. However, it does allow multiple interface inheritance. What will be the output of the following code? using System; public class BaseClass { public BaseClass() { Console.WriteLine("I am a base class"); } } public class ChildClass : BaseClass { public ChildClass() { Console.WriteLine("I am a child class"); } static void Main() { ChildClass CC = new ChildClass(); } } Output: I am a base clas...
Read more

C# Interview Questions on value types and reference types

-
What are the 2 types of data types available in C#? 1. Value Types 2. Reference Types If you define a user defined data type by using the struct keyword, Is it a a value type or reference type? Value Type If you define a user defined data type by using the class keyword, Is it a a value type or reference type? Reference type Are Value types sealed? Yes, Value types are sealed. What is the base class from which all value types are derived? System.ValueType Give examples for value types? Enum Struct Give examples for reference types? Class Delegate Array Interface What are the differences between value types and reference types? 1. Value types are stored on the stack where as reference types are stored on the managed heap. 2. Value type variables directly contain their values where as reference variables holds only a reference to the location of the object that is created on the managed heap. 3. There is no heap allocation or garbage collection overhead for value-type variables. As ...
Read more

Why to use UpdatePanel control in AJAX ASP.NET?

-
AJAX is a client side technology and it supports asynchronous communication between client and server. If the part of page need to be refreshed, then we can use this Update panel control, which uses AJAX request and does not harm the other part of the page. Using Update Panel improves the user experience of the page since it does not refresh the whole page.
Read more