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How do you add objects to hashtable
A) With Add methodB) With insert MethodC) With = operator
Kal_CSharp
- Jan 16th, 2008
See the example here:Hashtable ht = new Hashtable(); ht.Add(0, "Kals");ht.Add(1, "Kal"); (or)ht[0] = "ABC"; ht[1] = "XYZ";
Ashish
- Feb 5th, 2007
Object in the Hash table can be add with the add method as well as with "=" also.Hashtable h =new Hash Table()h.add(Key,Value)orh(Key)=valueThanks
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How do you refer parent classes in C#
A) SuperB) ThisC) Base
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How to implement multiple inheritence in C#
A) Using InterfaceB) Using Abstract classC) Using DelegatesD) Using Events
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How can you sort the elements of the array in descending order
A) Sort methodsB) Reverse methodsC) By calling Sort and then Reverse methodsD) Can’t sort in descending
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Editorial / Best Answer
Answered by: Prakhar
- Apr 12th, 2006
int[] arr = new int[3];
arr[0] = 4;
arr[1] = 1;
arr[2] = 5;Array.Sort(arr);
Array.Reverse(arr);rfb99
- Dec 16th, 2011
It is far more elegant and efficient to do something like
Array.Sort(arr, delegate(int x, int y) { return y.CompareTo(x); }); -
Where we can use DLL made in C#.Net
We can use the .net DLLs only in the applications supporting .NET.
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We have a dataset with one thousand records. Now we bind it to a datagrid. Now the question is suppose we have modified only three records in datagrid then how to update these three records in dataset. We have a single button to update the records
Max Headroom
- Jun 13th, 2008
Use the RowState property of the DataTable in the DataSet that the grid is bound to where RowState is Modified. You can do this in a number of ways, if you do a Select on the DataTable you can pass Ro...
manish sinha
- Jun 29th, 2007
Use dataset.GetChanges() method to return a modified copy of the dataset. This dataset will have only 3 records, modified ones.
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What are public, private and static constructors and differences between them?
Obiageligeorge
- Aug 23rd, 2011
A public constructor is accessible anywhere in the application
A private constructor is restricted to the class within the application
Static constructor give access to the data without necessarily creating an object classmd.shahidkamal
- Aug 22nd, 2011
Constructor are used for creating an object and returning a reference of the object. so whenever we write class1 obj=new class1(); Public Constructor The new Class1() is actually calling a public ze...
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What are multiple delegates?Can 2 delegates in a class can refer to a same method?
nikhilrawat23
- May 27th, 2008
multiple delegates and multicast delegates both are diffrent terms with diffrent aspects.delegate having one property that it could have multiple delegates in it.it means single delegates contain mult...
sajeesh
- Oct 17th, 2007
Multi cast delegates means a delegate can hold more than one methods but not vice versa.
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Only a 'Static' method can be called using delegate - True / False? Give Reason
Naveen Shivanadri
- Sep 18th, 2016
Using delegate, we can execute static method as well as instance method. By binding a method with delegate, we will use the instance if the method is instance method else method name if the method is static.
Naveen -
Abstract classes and virtual methods
Abstract classes can be overridden by virtual methods (true, false)
PeterVH
- Aug 19th, 2011
Hello Raj, you override methods, not classes. So, guessing you mean abstract methods. The overriding method can NEVER be virtual, but by using the "new" keyword you can *replace* the abstract method...
mahmood pasha
- Jul 1st, 2008
It is designed to act as derived class. the class , which contain more virtual function is called an abstract class. and it cannot be create as an object, and it is similar to Interface
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Variable Declaration and Assignment
What is difference between these two statement? if variable is declared and assign value in following two waysString sValue = (String)GridView1.DataKeys[GridView1.SelectedIndex].Value;String sValue = GridView1.DataKeys[GridView1.SelectedIndex].Value.ToString();
gispadhu
- Aug 19th, 2010
The first statement can handle null values whereas the second statement throws an exception.
hdkhanna
- May 18th, 2010
First statement:String sValue = (String)GridView1.DataKeys[GridView1.SelectedIndex].Value;The above statement uses type casting (explicit) to convert the value to string. Second statement:String sValu...
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Explicit Implimentation
What do you mean by Explicit Interface Implimentation? What's Interface Mapping?
azita2005
- Apr 5th, 2010
If we have a class inherits from interface, we need to implements the members of that interface. It is possibe with explicitly or implicitly way. In Explicit way, through the interface we ...
RajMarandi
- Oct 23rd, 2009
interface I1{ void someMethod();}Interface I1{ void someMethod();} class someClass:I1,I2{ void I1.someMethod() { ...
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Advantage of avl tree over binary search tree.
What is advantage using avl tree instead of using binary search tree ?
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Exception Handling
what is the necessary for "throws" and "throw" in exception handling??
Even Though the exception has been thrown automatically and being handled by try and catch block..
Suresh Jayaraman
- Sep 23rd, 2011
if we have different layers like Dataaccess layer,Business layer ,Presentation layer. The error is in DataAccess layer,that error should come to presentation layer and we can show that error in messa...
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Why do I get a syntax error when trying to declare a variable called checked?
The word checked is a keyword in C#.
Elean0r
- May 23rd, 2011
checked is a keyword in c#, which causes designated expressions to be checked for arithmetic overflow. It may be used in one of two ways:1) block - checked {} , where the block of statements enclosed ...
Vikas Yadav
- Apr 5th, 2008
Reason is checked is a keyword in C#,but if u want to keyword as an identifier use @ with it.e.g int @checked=3;This works with all the keywords,but it is recommended to avoid it.
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How do I create a Delegate/MulticastDelegate?
C# requires only a single parameter for delegates: the method address. Unlike other languages, where the programmer must specify an object reference and the method to invoke, C# can infer both pieces of information by just specifying the method's name. For example, let's use System.Threading.ThreadStart: Foo MyFoo = new Foo();ThreadStart del = new ThreadStart(MyFoo.Baz);This means that delegates can...
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Editorial / Best Answer
Answered by: Raghu
- Sep 29th, 2005
This article is good.
Introduction
In this article I am going to share my knowledge on Delegates in C#.This would explain the Delegate using simple examples so that the beginner can understand the same.What is Delegate?
Definition:
Delegate is type which holds the method(s) reference in an object.
it is also reffered as a type safe function pointers.
Advantages:
.Encapsulating the method's call from caller
.Effective use of Delegat improves the performance of application.
.used to call a method asynchronously.
Declaration:
public delegate type_of_delegate delegate_name()
Example : public delegate int mydelegate(int delvar1,int delvar2)
Note:
.you can use delegeate without parameter or with parameter list
.you should follow the same syntax as in the method
(if you are reffering the method with two int parameters and int return type the delegate which you are declaring should be the same format.This is how it
is reffered as type safe function pointer)
Sample Program using Delegate :
public delegate double Delegate_Prod(int a,int b);
class Class1
{
static double fn_Prodvalues(int val1,int val2)
{
return val1*val2;
}
static void Main(string[] args)
{
//Creating the Delegate Instance
Delegate_Prod delObj = new Delegate_Prod(fn_Prodvalues);
Console.Write("Please Enter Values");
int v1 = Int32.Parse(Console.ReadLine());
int v2 = Int32.Parse(Console.ReadLine());
//use a delegate for processing
double res = delObj(v1,v2);
Console.WriteLine ("Result :"+res);
Console.ReadLine();
}
}
Explanation:
Here I have used a small program which demonstrates the use of delegate.
The delegate "Delegate_Prod" is declared with double return type and which accepts only two integer parameters.
Inside the Class the method named fn_Prodvalues is defined with double return type and two integer parameters.(The delegate and method is having the same signature and parameters type)
Inside the Main method the delegate instance is created and the function name is passed to the
delegate instance as following.
Delegate_Prod delObj = new Delegate_Prod(fn_Prodvalues);
After this we are accepting the two values from the user and passing those values to the delegate as we do using method .
delObj(v1,v2);
Here delegate object encapsulates the method functionalities and return the result as we specified
in the method.Multicast Delegate
What is Multicast Delegate? :
It is a Delegate which holds the reference of more than one methods.
Multicast delegates must contain only methods that return void, else there is a run-time exception.
Simple Program using Multicast Delegate
----------------------------------------
delegate void Delegate_Multicast(int x, int y);
Class Class2
{
static void Method1(int x, int y) {
Console.WriteLine("You r in Method 1");
}
static void Method2(int x, int y) {
Console.WriteLine("You r in Method 2");
}
public static void Main()
{
Delegate_Multicast func = new Delegate_Multicast(Method1);
func += new Delegate_Multicast(Method2);
func(1,2); // Method1 and Method2 are called
func -= new Delegate_Multicast(Method1);
func(2,3); // Only Method2 is called
}
}
Explanation:
In the above example you can see that two methods are defined named method1 and method2 which takes two integer parameters and return type as void.
In the main method the Delegate object is created using the following statement
Delegate_Multicast func = new Delegate_Multicast(Method1);
Then the Delegate is added using the += operator and removed using -= operator.
Naveen Kumar Shivanadri
- Sep 8th, 2016
Delegate is not type. It is just pointer method which is used to improve the performance. Suppose we want to execute a method 10 times by using calling method by using class name or instance, 10 time...
Rajesh Muurya
- Aug 9th, 2016
I have some doubt.
Raghus Says: Delegate is type which holds the method(s) reference in an object.
My question is if Delegate is type then how we create a object of delegate? Because, we know that we can create object only struct and class. -
When you inherit a protected class-level variable, who is it available to?
Classes in the same namespace.
Basavarajayya
- Nov 14th, 2009
Its available only to the derived classes and not all the classes in the NameSpace
anil4kick
- Sep 26th, 2009
Protected level variable is available to only sub classes(i.e class inherited from this base class).
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What does the keyword virtual mean in the method definition?
The method can be over-ridden.
smandke
- Aug 27th, 2010
Virtual method in C# is a used to support polymorphism. This means that in a base class we will define a method foo1() with the keyword "virtual" and the derived classes will inherit t...
sahajanandk
- Mar 9th, 2009
Keyword virtual is used to make changes to the methods inside the virtual class while runtime. the virtual class should be overide with the same modifier, return type and the name.
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Can you change the value of a variable while debugging a C# application?
Yes, if you are debugging via Visual Studio.NET, just go to Immediate window.
C# Interview Questions
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