Interview » CSharp

Define interface in own words.

meghna — Sat, 21 May 2011 21:43:04 +0000

We have many books around, anyone can get a definition of interface which is nothing but bookish. In these days we are more interested to know what you know about interfaces rather than what you read for interfaces?

Here, I tried to cover interfaces in my own words:

Interface

An interface is simply a collection of function prototypes. An Interface is a reference type like a class, but interface can contain only abstract members. In other words, Interface is a contract that defines the signature of the functionality.

An interface looks like a class definitions, but its only purpose is to define a set of methods and not to implement them. For this reason the interface definition includes only the definition of methods [in other words the abstract methods]. Interface contains only methods, properties and delegates but can not contain fields, constructors, destructor and any type of static members.

For more details and example refer to : http://gauravarora.indiamentor.com/Chapters/csharplanguageii.htm

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What are Classes and structures

gaurav.arora — Wed, 18 May 2011 05:49:57 +0000

A very basic and common questions asked many time to freshers, novoice or intermediate level interviews. I got many emails for the same questions, hereunder I try to answer in a simpler way.

Structures

A structure in C# is simply a composite data type [you are well aware from composite data type, refer to data types for more details], which consists number of members of other types. The structure define simply by using the struct keyword.

eg. struct enroll
{
   public string name, fname, mname;
   public string char sex;
   Public int age;
   public string address;
}

Classes

It is cleared from above study that Classes are reference type. A class is a collection of its data members. Data members are those members of class which contains the data of class like fields, constants and events etc. Class is declared simply just followed by class keyword with optional modifiers; by default C# classes are public.

eg. class myClass
{
   public int xyz;
   public string name;
   public const int y=22;
}

Look into more details at : http://gauravarora.indiamentor.com/Chapters/csharplanguageii.htm

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Can I inherit two difference classes to partial classes?

smartbrain — Mon, 25 Jan 2010 14:50:50 +0000

Q. Can I inherit two difference classes to partial classes? Following is the whole scenario of this question:

I have two classes XYZ and ABC and two partial classes of class myClass now is it possible:

partial class myClass : XYZ

{

}

partial class myClass : ABC

{

}

Ans: This question I have asked in RSystems, Noida and I am sharing hereunder with you :

We can’t inherit two difference classes to partial class because in C# multiple inheritance is not possible using classes.

The main reason is in C# we cant do the following:

class myClass : XYZ, ABC

{

}

It will throw an error while we compile the code.

Note: if anyone has better views for this question please share.

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How can I create a Singleton class by using public constructor?

meghna — Mon, 11 Jan 2010 15:39:23 +0000

I have also asked a tricky question like this:

Can we create a singleton class using public constructor?

Simply answer is yes.

Practically, many of us aware that we can create a singleton class by using private constructor an creating a property, but we can create a singleton class by using public constructor as folows:

static void Main(string[] args)

{

try

{

Singleton obj3 = new Singleton2();

Singleton obj4 = new Singleton2();

Console.Read();

}

catch (Exception ex)

{

Console.WriteLine(ex.ToString());

Console.Read();

}

static void Main(string[] args)

{

try

{

Singleton obj3 = new Singleton2();

Singleton obj4 = new Singleton2();

Console.Read();

}

catch (Exception ex)

{

Console.WriteLine(ex.ToString());

Console.Read();

}

}