Can any 1 tell me few scenarios 4 using Interface in C#

Question

Hi all  I ve'nt use an Interface yet as I am really confuse abt its use. I have read in articles that When trying to build maintainable reusable and flexible C# code the object oriented nature of C# only gets us 50% of the way there. Programming to interfaces can provide us with the last 50%. Now if we go for Interface defination then :- An interface is a reference type object with no implementation. No properties or methods are actually coded in an interface they are only defined. So the interface doesn't actually do anything but only has a signature for interaction with other classes or interfaces. Can any one plz explain me how interface is the replacement of multiple inheritance of c++. If it has only signature of the methods then how it helps for multiple inheritence.How it increase code reusability. If possible plz give some codes and help me understand this little concepts. I have went through many articles but could'nt figure out where to use so that it will increase COde reusabilty. Thanks & Regards s_raj0205

Rahul Saxena · Answer

Hi We use interface in C# to achieve the functionality of Multiple Inheritance. In C# we can not inherit two class at a same time. Class A: ClassBClass c This is wrong But we can inherit more then one Interface Class A: InterfaceB InterfaceC This Is right

suraj rai · Answer

Hi thanx a lot...sumtime in future ..i will again bring out this discussing abt wat i understood in a saparate thread... and still i feel i will be having lots of question even then.... Anyway..a lots n lots of thanks to u ..forums are realy a heaven for developers like us.. Thanks & Regards s_raj0205

Maha · Answer

This website has 25 examples about Interface. http://www.java2s.com/Code/CSharp/Language-Basics/Interface.htm

Jan Montano · Answer

Transaction class is totally independent from User Class. Transaction Class deals with my transaction table in database. while User clas deals with my user Table in database. Maybe you're looking reuse as reusing implemented code. It's not the case with interface. Actually you're just reusing the architecture or the design or the interface itself. IDomainObject consists of calls to my database. By inheriting from IDomainObject I'm saying that this is a class for interfacing with my database. By inhering an abstract method Update I can modify it's behaviour which suits the appropriate update command for my transaction. or my user table.

suraj rai · Answer

Here is 'Transaction' class by any means related to 'User' class or Interface 'DomainObject'. It seems Transaction is a totaly independent class where you have delcared Insert  update and delete function. But as you ve reply for inteface ...is transaction class has anything to do with inteface 'DomainObject'. And how this code will be help full for reusing Insert Update and delete methods in Interface. Sory for killing ur valuable time... Hoping 4 ur reply. Thanks & Regards s_raj0205

Jan Montano · Answer

Here's a real world example. interface DomainObject { int Id { get; set; } void Insert(); void Update(); void Delete(); } class Transaction { private int id; private string code; private string amount; private string transactionDate; public int Id { get { return id; } set { id = value; } } public void Insert() { // insert into TransactionTable values (codeamounttransactionDate)... } public void Update() { // update TransactionTable where Id = id set code = code... } public void Delete() { // delete TransactionTable where Id = id... } } class User : DomainObject { private int id; private string firstName; private string middleName; private string lastName; public int Id { get { return id; } set { id = value; } } public void Insert() { // insert into UserTable values (firstnamemiddlenamelastname)... } public void Update() { // update userTable where Id = id set FirstName = firstname... } public void Delete() { // delete userTable where Id = id... } }

suraj rai · Answer

Hi Jan I really appreciate the way you explain...tat was really a nice example n help me to understand interface.. But stil i think the question of reusability remains there only as u said if I had to make an Eagle class I will inherit IEagle inteface and had to implement the 2 properties and the fly method again... Can u give me some real time projects example ..like while doing some database application in windows or any web application like ecommerce ..in such case wer we cn use Interface ... I think using Interface in all kind of application is not the right way.. Your precios time will be heighly appreciated...Plz reply.. Thanks & regards s_raj0205

Jan Montano · Answer

hmmm... How could i put this... Let's say I want to create a Gryphon Class. As a mythical creature a gryphon is Half Lion and Half eagle. Fortunately I already have a design for my Lion Class and Eagle class. And the gryphon being a lion and eagle I would want it to have the characteristics of a lion and an eagle. Not just the characteristics of either one of them but both. Here enters our interface. Instead of thinking of a way to design my gryphon class I just simply reuse or inherit my interface for lion and eagle then Voila! I can already implement my gryphon class. with no hassle. interface IEagle { int WingSpan { get; set; } int BeakSize { get; set; } void Fly(); } interface ILion { int TailLength { get; set; } string FurColor { get; set; } void Run(); } interface IGryphon : IEagle ILion { } class Gryphon : IGryphon { private int wingSpan; private int beakSize; private int tailLength; private string furColor; public int WingSpan { get { return wingSpan; } set { wingSpan = value; } } public int BeakSize { get { return beakSize; } set { beakSize = value; } } public int TailLength { get { return tailLength; } set { tailLength = value; } } public string FurColor { get { return furColor; } set { furColor = value; } } public void Fly() { Console.WriteLine(The gryphon is flying...); } public void Run() { Console.WriteLine(The gryphon is running...); } } You'll notice that if you remove just one method or one property from the gryphon class it will not compile because techinally it inherits from ILion and IEagle and as such I am forced to implement all the behaviours of ILion and IEagle. On the other hand if I want to make an Eagle Class I just have it implement IEagle. And I'll know exactly what I have to put in code for my Eagle Class. Hope this makes sense. Good luck. It took me half a day arriving with this idea. hahaha! (^_^)