Asp.net and C#.net Tips

Tips to Improve ASP dotnet Application Performance

2013-10-14T22:29:00.000-07:00

There are certain things you should take into account when you are developing your applications.

I have learned to avoid and do certain things that increase your application performance by a massive amount!

1)Avoid Server-Side Validation

Try to avoid server-side validation, use client-side instead. Server-Side will just consume valuable resources on your servers, and cause more chat back and forth.

2)Repeater Control Good as Compare to DataList, DataGrid, and DataView controls.

Asp.net is a great platform, unfortunately a lot of the controls that were developed are heavy in html, and create not the greatest scaleable html from a performance standpoint. ASP.net repeater control is awesome! Use it! You might write more code, but you will thank me in the long run!

3)Always check Page.IsValid when using Validator Controls

So you’ve dropped on some validator controls, and you think your good to go because ASP.net does everything for you! Right? Wrong! All that happens if bad data is received is the IsValid flag is set to false. So make sure you check Page.IsValid before processing your forms!

4)Page.IsPostBack

Make sure you don’t execute code needlessly. I don’t know how many web developers forget about checking IsPostBack! It seems like such a basic thing to me! Needless processing!

5)Avoid Exceptions

Avoid throwing exceptions, and handling useless exceptions. Exceptions are probably one of the heaviest resource hogs and causes of slowdowns you will ever see in web applications, as well as windows applications. Write your code so they don’t happen! Don’t code by exception!

6)Turn Off ViewState

If you are not using form postback, turn off viewsate, by default, controls will turn on viewsate and slow your site.Example :-if You Have Used Lable to display name static.

ForeColor="Red" EnableViewState="false">

7)Use the Finally Method

If you have opened any connections to the database, or files, etc, make sure that you close them at the end! The Finally block is really the best place to do so, as it is the only block of code that will surely execute.

COALESCE Function In Sql Server

2011-10-11T05:05:00.000-07:00

During Development we have use more time Colesce method If someone have home address or office address suppose if you dispaly available first record means you can use coalesce method or concatinate columns we use this coding

I have Below Table :

Insert Some Data in it :

Now the basic use of Colesce:
You can see the Id 2 hasnot OfficePhoneNo and id 5 has only MobileNo.
Colesce function can display available first record from one of the column.

It's Query Like :

select name ,coalesce(OfficePhoneNo,HomePhoneNo,MobileNo)
PhoneNo from EmpDetails

and Result will be :

Now I can show you another example of it.

We can also use coalesce function for Combining all column into single column.

CREATE TABLE Emp(FName VARCHAR(25))

INSERT INTO Emp VALUES('PalPatel')
INSERT INTO Emp VALUES('DishaAgola')
INSERT INTO Emp VALUES('Bansi')
INSERT INTO Emp VALUES('Nirav')


DECLARE @nam NVARCHAR(1024)

SELECT @nam=COALESCE(@nam+',', '')+ FName FROM Emp

SELECT Emp= @nam

Output :

PalPatel,DishaAgola,Bansi,Nirav

Thats it .....

Dynamically Load Webuser Control with Properties.

2011-09-16T04:55:00.000-07:00

Create a new class to act as the base control:

public class MyBaseControl : System.Web.UI.UserControl
{
    public string MyProperty 
    {
        get { return ViewState["MyProp"] as string; }
        set { ViewState["MyProp"] = value; }
    }
}

Then update your user controls to inherit from your base class instead of UserControl:

public partial class SampleControl2 : MyBaseControl
{
....
Then, in the place where you load the controls, change this:

UserControl uc = (UserControl)LoadControl(controlPath);
PlaceHolder1.Controls.Add(uc);

To:

MyBaseControl uc = (MyBaseControl)LoadControl(controlPath);
uc.MyProperty = "foo";
PlaceHolder1.Controls.Add(uc);

Any suggestions will be appreciated greatly. !!.

Get Data from Excel To Sql Server Using Asp.net

2011-09-16T04:54:00.000-07:00

Here I am going to show you the step by step process to import data from Excel to SQL Server. To do so follow the below steps :

Step:1 Create Sample Table.

 GO  
 CREATE TABLE [dbo].[Product_Master](  
   [Product_Code] [varchar](20) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,  
   [Product_Name] [varchar](100) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,  
   [Price] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL  
 ) ON [PRIMARY]  
 GO

Step:2 Create New Web site with new webpage named as Default.aspx (Following is the code contained in the Default.aspx page).

1:  <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>  
2:  <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">  
3:  <html xmlns="http://www.w3.org/1999/xhtml">  
4:  <head runat="server">  
5:    <title>Import Excel Data To SQL Server</title>  
6:  </head>  
7:  <body>  
8:    <form id="form1" runat="server">  
9:    <div>  
10:      <asp:Label ID="lblHeading" runat="server" Text="Select File To Upload : "></asp:Label>  
11:      <asp:FileUpload ID="FileUpload1" runat="server" />  
12:      <br />  
13:      <br />  
14:      <asp:Button ID="btnUpload" runat="server" Text="Upload"   
15:        onclick="btnUpload_Click" />     
16:      <asp:Button ID="btnSaveToDB" runat="server" Text="Save To DB"   
17:        onclick="btnSaveToDB_Click" />  
18:        <br /><br />  
19:      <asp:Label ID="lblerror" runat="server" ForeColor ="Red" Text=""></asp:Label>  
20:    </div>  
21:    </form>  
22:  </body>  
23:  </html>

Step:3 Here is the C# code of the Default.aspx.cs file:

1:  using System;  
2:  using System.Configuration;  
3:  using System.Data;  
4:  using System.Linq;  
5:  using System.Web;  
6:  using System.Web.Security;  
7:  using System.Web.UI;  
8:  using System.Web.UI.HtmlControls;  
9:  using System.Web.UI.WebControls;  
10:  using System.Web.UI.WebControls.WebParts;  
11:  using System.Xml.Linq;  
12:  using System.IO;  
13:  public partial class _Default : System.Web.UI.Page   
14:  {  
15:    protected void Page_Load(object sender, EventArgs e)  
16:    {  
17:    }  
18:    protected void btnUpload_Click(object sender, EventArgs e)  
19:    {  
20:      if (FileUpload1.HasFile)  
21:      {  
22:        var uploadFile = new UploadFile(FileUpload1.FileName);  
23:        try  
24:        {  
25:          FileUpload1.SaveAs(uploadFile.SavePath);  
26:        }  
27:        catch (Exception ex)  
28:        {  
29:          lblerror.Text = "error : "+ex.Message;  
30:        }  
31:       }  
32:    }  
33:    protected void btnSaveToDB_Click(object sender, EventArgs e)  
34:    {  
35:      ImportDataIntoDB idid = new ImportDataIntoDB();  
36:      string count = idid.saveDataToDB();  
37:      if (Convert.ToInt16(count) < 0)  
38:      {  
39:        lblerror.Text = "Error Occurred...";  
40:      }  
41:      UploadFile upFile = new UploadFile();  
42:      upFile.DeleteFileNoException();  
43:    }  
44:  }

Step:4 In this i call the UploadFile class which is created in a separate class file. This class is used to store uploaded file and also used to generate OleDb connection string as per file selected. Here is the code of UploadFile Class :

1:  using System;  
2:  using System.Data;  
3:  using System.Configuration;  
4:  using System.Linq;  
5:  using System.Web;  
6:  using System.Web.Security;  
7:  using System.Web.UI;  
8:  using System.Web.UI.HtmlControls;  
9:  using System.Web.UI.WebControls;  
10:  using System.Web.UI.WebControls.WebParts;  
11:  using System.Xml.Linq;  
12:  using System.IO;  
13:  ///   
14:  /// Summary description for UploadFile  
15:  ///   
16:  public class UploadFile  
17:  {  
18:    private string savePath;  
19:    public UploadFile()  
20:    {  
21:    }  
22:    public UploadFile(string originalFileName)  
23:    {  
24:      string tempFileName = Guid.NewGuid().ToString("N") + "_" + originalFileName;  
25:      string saveLocation = HttpContext.Current.Server.MapPath(ConfigurationManager.AppSettings["FileUploadLocation"]);  
26:      savePath = Path.Combine(saveLocation, tempFileName);  
27:      HttpContext.Current.Session["savePath"] = savePath;  
28:    }  
29:    ///   
30:    /// Temp path used to save the uploaded file  
31:    ///   
32:    public string SavePath  
33:    {  
34:      get  
35:      {  
36:        return savePath;  
37:      }  
38:    }  
39:    ///   
40:    /// Attempt to delete temp file  
41:    ///   
42:    public void DeleteFileNoException()  
43:    {  
44:      savePath = HttpContext.Current.Session["savePath"].ToString();  
45:      if (File.Exists(savePath))  
46:      {  
47:        try  
48:        {  
49:          File.Delete(savePath);  
50:        }  
51:        catch { }  
52:      }  
53:    }  
54:    ///   
55:    /// Return connection strinng based on file extension  
56:    ///   
57:    public string GetOleDbConnectionString()  
58:    {  
59:      savePath = HttpContext.Current.Session["savePath"].ToString();  
60:      var finfo = new FileInfo(savePath);  
61:      if (!finfo.Exists)  
62:      {  
63:        throw new FileNotFoundException(savePath);  
64:      }  
65:      var fileExtension = finfo.Extension.ToLower();  
66:      switch (fileExtension)  
67:      {  
68:        case ".xls":  
69:          return string.Format(ConfigurationManager.AppSettings["xlsOleDBConnection"], savePath);  
70:        case ".xlsx":  
71:          return string.Format(ConfigurationManager.AppSettings["xlsxOleDBConnection"], savePath);  
72:        default:  
73:          throw new NotSupportedException(String.Format("This file type {0} is not supported!", fileExtension));  
74:      }  
75:    }  
76:  }

Step:5 Now next step is read that file and save the data into sql server. Here is the method which reads the data from excel and save it into sql server database :

1:  public string saveDataToDB()  
2:    {  
3:      int j = 0;  
4:      string strQuery = "SELECT ProductCode,ProductName,ItemCaptionJP,ItemTextJP,IngredientsJP,CountryOfOrigin,HowToStore FROM [Sheet1$]";  
5:      DataTable dt = new DataTable();  
6:      OleDbCommand ocmd = new OleDbCommand(strQuery, oleconn);  
7:      //OleDbDataAdapter da = new OleDbDataAdapter(strQuery, oleconn);  
8:      oleconn.Open();  
9:      OleDbDataReader odr = ocmd.ExecuteReader();  
10:      int i = 0;  
11:      if (odr.HasRows)  
12:      {  
13:        while (odr.Read())  
14:        {  
15:          if (i == 0)  
16:            sb.Append("UPDATE Product_Master set [itemCaption_jp]=N'" + odr["ItemCaptionJP"] + "',[itemText_jp]=N'" + odr["ItemTextJP"].ToString() + "',[ingredients_jp]=N'" + odr["IngredientsJP"].ToString() + "',[countryoforigin_jp]=N'" + odr["CountryOfOrigin"].ToString() + "',[howtostore_jp]=N'" + odr["HowToStore"].ToString() + "' where [alternate_code]='" + odr["ProductCode"].ToString() + "' and Product_Name='" + odr["ProductName"].ToString() + "'");  
17:          else  
18:            sb.Append(";UPDATE Product_Master set [itemCaption_jp]=N'" + odr["ItemCaptionJP"] + "',[itemText_jp]=N'" + odr["ItemTextJP"].ToString() + "',[ingredients_jp]=N'" + odr["IngredientsJP"].ToString() + "',[countryoforigin_jp]=N'" + odr["CountryOfOrigin"].ToString() + "',[howtostore_jp]=N'" + odr["HowToStore"].ToString() + "' where [alternate_code]='" + odr["ProductCode"].ToString() + "' and Product_Name='" + odr["ProductName"].ToString() + "'");  
19:          i++;  
20:        }  
21:        j = UpdatedCommand(sb.ToString());  
22:      }  
23:      return j.ToString();  
24:    }  
25:    #region update,delete,insert data in Database  
26:    public int UpdatedCommand(string strupdatequery)  
27:    {  
28:      int intreturn = 0;  
29:      ClientScriptManager cs = Page.ClientScript;  
30:      Type ty = this.GetType();  
31:      try  
32:      {  
33:        SqlCommand cmdupdatecommand = new SqlCommand();  
34:        transsql = null;  
35:        if (sqlconn.State != ConnectionState.Closed)  
36:        {  
37:          sqlconn.Close();  
38:        }  
39:        sqlconn.Open();  
40:        transsql = sqlconn.BeginTransaction();  
41:        cmdupdatecommand.CommandTimeout = 0;  
42:        cmdupdatecommand.CommandText = strupdatequery;  
43:        cmdupdatecommand.Connection = sqlconn;  
44:        cmdupdatecommand.Transaction = transsql;  
45:        intreturn = cmdupdatecommand.ExecuteNonQuery();  
46:        transsql.Commit();  
47:        if (sqlconn.State != ConnectionState.Closed)  
48:        {  
49:          sqlconn.Close();  
50:        }  
51:        return intreturn;  
52:      }  
53:      catch (SqlException oleex)  
54:      {  
55:        transsql.Rollback();  
56:        strupdatequery = oleex.Message;  
57:        strerorrmsg1 = "Error In UpdatedCommand method " + oleex.Message.ToString();  
58:        strerorrmsg2 = strerorrmsg1.Replace("'", "");  
59:        string msg = "alert('" + strerorrmsg2 + "');";  
60:        cs.RegisterStartupScript(ty, strerorrmsg1, msg, true);  
61:        return -3;  
62:      }  
63:      catch (System.Exception exp)  
64:      {  
65:        transsql.Rollback();  
66:        strupdatequery = exp.Message;  
67:        strerorrmsg1 = "Error In UpdatedCommand method " + exp.Message.ToString();  
68:        strerorrmsg2 = strerorrmsg1.Replace("'", "");  
69:        string msg = "alert('" + strerorrmsg2 + "');";  
70:        cs.RegisterStartupScript(ty, strerorrmsg1, msg, true);  
71:        return -3;  
72:      }  
73:      finally  
74:      {  
75:        if (sqlconn.State != ConnectionState.Closed)  
76:        {  
77:          sqlconn.Close();  
78:        }  
79:      }  
80:    }  
81:    #endregion

4 Small But Important Tips For Fresher of Asp.net.

2011-09-13T04:12:00.000-07:00

Asp.net is a awesome framework developing web sites and web applications.with visual studio asp.net become cooler and cooler. I have wrote an article Visual Studio 2010 New Tips and Shortcut previously. now I thought to write for asp.net tips and tricks because as the way you are using the framework it’ll be hard or easier to understand and do some work with minimum codes.
Ok here we go we’ll see what are the cool features offer asp.net for .net web developers.

1. Maintain the position of scrollbar on postback : since asp.net 1.1 it was a very hard to maintain the position of scrollbar when doing postback. it’s was very necessary feature when we edit some data and after submit find position that we were editing. In asp.net 2.0 you can simply add the MantainScrollPositionOnPostBack attribute to the page directive.

<%@ Page Language="C#" MaintainScrollPositionOnPostback="true" AutoEventWireup="true" CodeFile="..." Inherits="..." %>

2. Set Default Button for form when user hit the enter key : In asp.net 1.1 required to write javascript to set default key for when form submit after hit Enter key. fortunatly you can use HtmlForcontrol’s DefaultButton property to set which button should be clicked when the user hit the enter

<form id="frm" DefaultButton="btnSubmit" runat="server">

...

</form>

3. Set the default focus to control when page loads : as mention above also we can set default focus for page load like below

<form id="frm" DefaultFocus="txtUserName" runat="server">

...

</form>

4. Strongly type access to the cross-page postbacks : asp.net 2.0 introduced the concept of cross page post back where one page could post back information to another page.if you add public property in to code behind page that initiate the postback operation, you can access property in strong type manner by adding PreviouPageType directive in to target page of the post back.
<%@ PreviousPageType VirtualPath="Default.aspx" %>

by adding this directive to pageyou can access the TextBox defind in previous page in strongly type manner.

TextBox tb = PreviousPage.SearchTextBox;

Show/Hide ModalPopup Using Javascript.

2011-09-05T01:42:00.000-07:00

The Asp.net Markup :

<asp:panel id="pnlDemo" runat="server" style="display: none;">
<h1> This panel is a test demo</h1> </asp:panel>

<cc1:modalpopupextender backgroundcssclass="modalBlockBackground" behaviorid="ModalPopupExtender" dynamicservicepath="" enabled="True" id="ModalPopupExtender" popupcontrolid="pnlDemo" runat="server" targetcontrolid="linkButton1"> </cc1:modalpopupextender>

If we want to use the javascript to control the popup, we can just simply to write the code like this:

if(!show)
{
$find('ModalPopupExtender').hide();
}
else
{
$find("ModalPopupExtender").show();
}

There is one thing need to be taken care which is the BehavirID, the code in the Javasctipt will look for the BehaviorID property for the ModalPopupExtender.

I hope this can be helpful for you.

3 Things Must You Know About C# Code.

2011-09-01T22:32:00.000-07:00

1. Null Coalescing Operator (??)

A new operator can be used which can be shortcut of ternary operator to check the null value:

Ternary operator (?:):

string empName = (value != null) ? value : string.Empty;

we can write it using null-coalescing operator (??):

string empName = value ?? string.Empty;

2. The As Cast

we might have seen the code something like:
if (customer is DeluxCustomer)
{
var dCust = (DeluxCustomer)customer
// ...
}

This is redundant because we are checking the type twice. Once in the is check and once in the cast.

We can use as operator in place. This will cast the type if the types are compatible, or return null if not:
var dCust = customer as DeluxCustomer;
// ... we can write if condition to check for null
}

we can avoid double-checking the type.

3. Auto-Properties

This is the new concept to define the properties in C#: we can define the auto-property without much code:
public class Name

{
public int name { get; set; }
public int name { get; set; }
}

How To Read Local Drive Information With Asp.net Application

2011-08-19T03:15:00.000-07:00

Some time we need to interact with the local file system, reading structure of the Directories, reading and writing files, or performing many other jobs.

In this Application we need use System.IO Namespace for working with file system directories. System.IO Contain Driveinfo class.

Driveinfo class is used to get information such us the name,type, and status of each drive.

DriveInfo DriveDetails= new DriveInfo(@"C:\");

DriveDetails.Name : it is used to get the name of the specified drive.

DriveDetails.DriveType : it is used to get type of the specified drive.

DriveDetails.AvailableFreeSpace : it is used to get the available free space in the specified drive.

DriveDetails.TotalFreeSpace :it is used to get the total free space in the specified drive.

DriveDetails.TotalSize :it is used to get the total size in the specified drive.

DriveDetails.DriveFormat : it is used to get the format of the specified drive.

Here I am Getting C drive Information such us Drive Name, Drive Type, Free Space, Drive Format, Total Free Space, Total Size.

Here i am getting drive Size is in bytes. but i want result in Giga Bytes.

1024 Bytes = 1 KiloByte(KB)
1024 KiloBytes(KB) = 1 MegaByte(MB)
1024 MegaBytes(MB) = 1 GigaByte(GB)
1024 GigaBytes(GB) = 1 TeraByte(TB)

I am converting Bytes to Giga bytes.

double db = Convert.ToDouble(lblTotalSize.Text);
double db1 = db / 1024;
double db2 = db1 / 1024;
int db3 = Convert.ToInt32(db2) / 1024;

protected void Page_Load(object sender, EventArgs e)

{

DriveInfo DriveDetails= new DriveInfo(@"C:\");

lblDriveName.Text = DriveDetails.Name;

lblDriveType.Text = DriveDetails.DriveType.ToString();

lblFreeSpace.Text = DriveDetails.AvailableFreeSpace.ToString();

lblDriveFormat.Text = DriveDetails.DriveFormat.ToString();

lblTotalFreeSpace.Text = DriveDetails.TotalFreeSpace.ToString();

lblTotalSize.Text = DriveDetails.TotalSize.ToString();

double db = Convert.ToDouble(lblTotalSize.Text);

double db1 = db / 1024;

double db2 = db1 / 1024;

int db3 = Convert.ToInt32(db2) / 1024;

lblTotalSizeInGb.Text = db3.ToString() + " GB";

double TS = Convert.ToDouble(lblTotalFreeSpace.Text);

double TS1 = TS / 1024;

double TS2 = TS1 / 1024;

int TS3 = Convert.ToInt32(TS2) / 1024;

lblTotalFreeSpaceGB.Text = TS3.ToString() + " GB";

}

Now you can understand about How to read Drive information from local System using Asp.Net Web application AND to calculate Bytes to Giga bytes in Web Application

If you find a bug and have a fix for it: please let me know and I'll be happy to update the code I am hosting here.

Any suggestions will be appreciated greatly.

varchar Vs. nvarchar

2011-02-05T23:53:00.000-08:00

char, nchar, varchar, and nvarchar each take a length parameter which the database engine can use to optimize storage.

UTF-16 (when sticking to the BMP) has a simple two-to-one relationship between bytes of storage and characters, which the database can take advantage of.

The amount of storage required for a UTF-8 string of N characters is not as clear, and could result in wasted space, or unexpectedly truncated strings.

varchar does not store ASCII, it stores an 8-bit encoding.

nvarchar and varchar do not "function identically" since varchar does not function at all in lots of scenarios.

varchar contain max size 8000 while nvarchar size is 4000.

nvarchar may take up twice as much space, but varchar is twice as slow, since it requires string conversions for every read and write (on those occasions when it actually works).

About AJAX !!

2010-08-19T19:44:00.000-07:00

What is Ajax ??

Ajax is a way of developing Web applications that combines:

    * XHTML and CSS standards based presentation
    * Interaction with the page through the DOM
    * Data interchange with XML and XSLT
    * Asynchronous data retrieval with XMLHttpRequest
    * JavaScript to tie it all together

In the traditional Web application, the interaction between the customer and the server goes like this:

   1. Customer accesses Web application
   2. Server processes request and sends data to the browser while the customer waits
   3. Customer clicks on a link or interacts with the application
   4. Server processes request and sends data back to the browser while the customer waits
   5. etc....

There is a lot of customer waiting.

Ajax Acts as an Intermediary

The Ajax engine works within the Web browser (through JavaScript and the DOM) to render the Web application and handle any requests that the customer might have of the Web server. The beauty of it is that because the Ajax engine is handling the requests, it can hold most information in the engine itself, while allowing the interaction with the application and the customer to happen asynchronously and independently of any interaction with the server.

Asynchronous

This is the key. In standard Web applications, the interaction between the customer and the server is synchronous. This means that one has to happen after the other. If a customer clicks a link, the request is sent to the server, which then sends the results back.

With Ajax, the JavaScript that is loaded when the page loads handles most of the basic tasks such as data validation and manipulation, as well as display rendering the Ajax engine handles without a trip to the server. At the same time that it is making display changes for the customer, it is sending data back and forth to the server. But the data transfer is not dependent upon actions of the customer.
Ajax is Not New Technology

Ajax is instead a new way of looking at technology that is already mature and stable. If you're designing Web applications right now, why aren't you using Ajax? Your customers will thank you, and frankly, it's just fun!

That's It ..!!

How to Store Values In View State..??

2010-08-19T00:05:00.000-07:00

ASP.NET has a built in mechanism for storing values of controls known as ViewState.
The ViewState property provides a key-value object for storing values between multiple requests of the same page.
ASP.NET saves the state of the page and controls as a hashed string in the page as a hidden variable, ViewState.
When a page is run, the ViewState property can be seen from the source code of the page.

<input type="hidden" name="__EVENTVALIDATION" id="__EVENTVALIDATION" 
value="/wEWAgL3ku32BwLs0bLrBqcPjj4o1kvxlT2D91sy/YSkJDTh" />

Custom data can be stored in the ViewState property.

If a value has to be stored for a user in page, ViewState is an easy way to achieve this.
Please note that ViewState property is only accessible from the page only.
If the user visits a different page, the ViewState property will be lost.

Let's create a string containing a date and store it in the ViewState.

string date = DateTime.Now.ToString();

ViewState["date"] = date;

An alternative way of achieving this would be to


ViewState.Add("date", date);


The values stored in the ViewState can also be retrieved as follows.


if ((string)ViewState["date"] != null)

{

string date2 = (string)ViewState["date"];

}

>

Here, I am checking there a ViewState property named "date". If so, assign the value to string date2.
In ViewState, objects can also be stored/ For example, we can store a DateTime object like below

ViewState.Add("date3", DateTime.Now);

and retrieve the object like

DateTime date3 = (DateTime)ViewState["date3"];

That's It....!!

C#.net Interview Question & Answer...!!

2010-07-11T04:32:00.000-07:00

General Questions

Does C# support multiple-inheritance?
No.
Who is a protected class-level variable available to?
It is available to any sub-class (a class inheriting this class).
Are private class-level variables inherited?
Yes, but they are not accessible. Although they are not visible or accessible via the class interface, they are inherited.
Describe the accessibility modifier “protected internal”.
It is available to classes that are within the same assembly and derived from the specified base class.
What’s the top .NET class that everything is derived from?
System.Object.
What does the term immutable mean?
The data value may not be changed. Note: The variable value may be changed, but the original immutable data value was discarded and a new data value was created in memory.
What’s the difference between System.String and System.Text.StringBuilder classes?
System.String is immutable. System.StringBuilder was designed with the purpose of having a mutable string where a variety of operations can be performed.
What’s the advantage of using System.Text.StringBuilder over System.String?
StringBuilder is more efficient in cases where there is a large amount of string manipulation. Strings are immutable, so each time a string is changed, a new instance in memory is created.
Can you store multiple data types in System.Array?
No.
What’s the difference between the System.Array.CopyTo() and System.Array.Clone()?
The Clone() method returns a new array (a shallow copy) object containing all the elements in the original array. The CopyTo() method copies the elements into another existing array. Both perform a shallow copy. A shallow copy means the contents (each array element) contains references to the same object as the elements in the original array. A deep copy (which neither of these methods performs) would create a new instance of each element's object, resulting in a different, yet identacle object.
How can you sort the elements of the array in descending order?
By calling Sort() and then Reverse() methods.
What’s the .NET collection class that allows an element to be accessed using a unique key?
HashTable.
What class is underneath the SortedList class?
A sorted HashTable.
Will the finally block get executed if an exception has not occurred?
Yes.
What’s the C# syntax to catch any possible exception?
A catch block that catches the exception of type System.Exception. You can also omit the parameter data type in this case and just write catch {}.
Can multiple catch blocks be executed for a single try statement?
No. Once the proper catch block processed, control is transferred to the finally block (if there are any).
Explain the three services model commonly know as a three-tier application.
Presentation (UI), Business (logic and underlying code) and Data (from storage or other sources).

Class Questions

What is the syntax to inherit from a class in C#?
Place a colon and then the name of the base class.
Example: class MyNewClass : MyBaseClass
Can you prevent your class from being inherited by another class?
Yes. The keyword “sealed” will prevent the class from being inherited.
Can you allow a class to be inherited, but prevent the method from being over-ridden?
Yes. Just leave the class public and make the method sealed.
What’s an abstract class?
A class that cannot be instantiated. An abstract class is a class that must be inherited and have the methods overridden. An abstract class is essentially a blueprint for a class without any implementation.
When do you absolutely have to declare a class as abstract?
1. When the class itself is inherited from an abstract class, but not all base abstract methods have been overridden.
2. When at least one of the methods in the class is abstract.
What is an interface class?
Interfaces, like classes, define a set of properties, methods, and events. But unlike classes, interfaces do not provide implementation. They are implemented by classes, and defined as separate entities from classes.
Why can’t you specify the accessibility modifier for methods inside the interface?
They all must be public, and are therefore public by default.
Can you inherit multiple interfaces?
Yes. .NET does support multiple interfaces.
What happens if you inherit multiple interfaces and they have conflicting method names?
It’s up to you to implement the method inside your own class, so implementation is left entirely up to you. This might cause a problem on a higher-level scale if similarly named methods from different interfaces expect different data, but as far as compiler cares you’re okay.
To Do: Investigate
What’s the difference between an interface and abstract class?
In an interface class, all methods are abstract - there is no implementation. In an abstract class some methods can be concrete. In an interface class, no accessibility modifiers are allowed. An abstract class may have accessibility modifiers.
What is the difference between a Struct and a Class?
Structs are value-type variables and are thus saved on the stack, additional overhead but faster retrieval. Another difference is that structs cannot inherit.

Method and Property Questions

What’s the implicit name of the parameter that gets passed into the set method/property of a class?
Value. The data type of the value parameter is defined by whatever data type the property is declared as.
What does the keyword “virtual” declare for a method or property?
The method or property can be overridden.
How is method overriding different from method overloading?
When overriding a method, you change the behavior of the method for the derived class. Overloading a method simply involves having another method with the same name within the class.
Can you declare an override method to be static if the original method is not static?
No. The signature of the virtual method must remain the same. (Note: Only the keyword virtual is changed to keyword override)
What are the different ways a method can be overloaded?
Different parameter data types, different number of parameters, different order of parameters.
If a base class has a number of overloaded constructors, and an inheriting class has a number of overloaded constructors; can you enforce a call from an inherited constructor to a specific base constructor?
Yes, just place a colon, and then keyword base (parameter list to invoke the appropriate constructor) in the overloaded constructor definition inside the inherited class.

Events and Delegates

What’s a delegate?
A delegate object encapsulates a reference to a method.
What’s a multicast delegate?
A delegate that has multiple handlers assigned to it. Each assigned handler (method) is called.

XML Documentation Questions

Is XML case-sensitive?
Yes.
What’s the difference between // comments, /* */ comments and /// comments?
Single-line comments, multi-line comments, and XML documentation comments.
How do you generate documentation from the C# file commented properly with a command-line compiler?
Compile it with the /doc switch.

Debugging and Testing Questions

What debugging tools come with the .NET SDK?
1. CorDBG – command-line debugger. To use CorDbg, you must compile the original C# file using the /debug switch.
2. DbgCLR – graphic debugger. Visual Studio .NET uses the DbgCLR.
What does assert() method do?
In debug compilation, assert takes in a Boolean condition as a parameter, and shows the error dialog if the condition is false. The program proceeds without any interruption if the condition is true.
What’s the difference between the Debug class and Trace class?
Documentation looks the same. Use Debug class for debug builds, use Trace class for both debug and release builds.
Why are there five tracing levels in System.Diagnostics.TraceSwitcher?
The tracing dumps can be quite verbose. For applications that are constantly running you run the risk of overloading the machine and the hard drive. Five levels range from None to Verbose, allowing you to fine-tune the tracing activities.
Where is the output of TextWriterTraceListener redirected?
To the Console or a text file depending on the parameter passed to the constructor.
How do you debug an ASP.NET Web application?
Attach the aspnet_wp.exe process to the DbgClr debugger.
What are three test cases you should go through in unit testing?
1.       Positive test cases (correct data, correct output).
2.       Negative test cases (broken or missing data, proper handling).
3.       Exception test cases (exceptions are thrown and caught properly).
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.

ADO.NET and Database Questions

What is the role of the DataReader class in ADO.NET connections?
It returns a read-only, forward-only rowset from the data source. A DataReader provides fast access when a forward-only sequential read is needed.

What are advantages and disadvantages of Microsoft-provided data provider classes in ADO.NET?
SQLServer.NET data provider is high-speed and robust, but requires SQL Server license purchased from Microsoft. OLE-DB.NET is universal for accessing other sources, like Oracle, DB2, Microsoft Access and Informix. OLE-DB.NET is a .NET layer on top of the OLE layer, so it’s not as fastest and efficient as SqlServer.NET.
What is the wildcard character in SQL?
Let’s say you want to query database with LIKE for all employees whose name starts with La. The wildcard character is %, the proper query with LIKE would involve ‘La%’.
Explain ACID rule of thumb for transactions.
A transaction must be:
1.       Atomic - it is one unit of work and does not dependent on previous and following transactions.
2.       Consistent - data is either committed or roll back, no “in-between” case where something has been updated and something hasn’t.
3.       Isolated - no transaction sees the intermediate results of the current transaction).
4.       Durable - the values persist if the data had been committed even if the system crashes right after.
What connections does Microsoft SQL Server support?
Windows Authentication (via Active Directory) and SQL Server authentication (via Microsoft SQL Server username and password).
Between Windows Authentication and SQL Server Authentication, which one is trusted and which one is untrusted?
Windows Authentication is trusted because the username and password are checked with the Active Directory, the SQL Server authentication is untrusted, since SQL Server is the only verifier participating in the transaction.
What does the Initial Catalog parameter define in the connection string?
The database name to connect to.
What does the Dispose method do with the connection object?
Deletes it from the memory.
To Do: answer better. The current answer is not entirely correct.
What is a pre-requisite for connection pooling?
Multiple processes must agree that they will share the same connection, where every parameter is the same, including the security settings. The connection string must be identical.

Assembly Questions

How is the DLL Hell problem solved in .NET?
Assembly versioning allows the application to specify not only the library it needs to run (which was available under Win32), but also the version of the assembly.
What are the ways to deploy an assembly?
An MSI installer, a CAB archive, and XCOPY command.
What is a satellite assembly?
When you write a multilingual or multi-cultural application in .NET, and want to distribute the core application separately from the localized modules, the localized assemblies that modify the core application are called satellite assemblies.
What namespaces are necessary to create a localized application?
System.Globalization and System.Resources.
What is the smallest unit of execution in .NET?
an Assembly.
When should you call the garbage collector in .NET?
As a good rule, you should not call the garbage collector. However, you could call the garbage collector when you are done using a large object (or set of objects) to force the garbage collector to dispose of those very large objects from memory. However, this is usually not a good practice.
How do you convert a value-type to a reference-type?
Use Boxing.
What happens in memory when you Box and Unbox a value-type?
Boxing converts a value-type to a reference-type, thus storing the object on the heap. Unboxing converts a reference-type to a value-type, thus storing the value on the stack.

Asp.net Interview Question.....!!

2010-07-11T04:09:00.000-07:00

There are some questions in this list that I do not consider to be good questions for an interview. However, they do exist on other lists available on the Internet so I felt compelled to keep them here for easy access.

Describe the role of inetinfo.exe, aspnet_isapi.dll andaspnet_wp.exe in the page loading process.
inetinfo.exe is theMicrosoft IIS server running, handling ASP.NET requests among other things.When an ASP.NET request is received (usually a file with .aspx extension), the ISAPI filter aspnet_isapi.dll takes care of it by passing the request tothe actual worker process aspnet_wp.exe.
What’s the difference between Response.Write() andResponse.Output.Write()?
Response.Output.Write() allows you to write formatted output.
What methods are fired during the page load?
Init() - when the page is instantiated
Load() - when the page is loaded into server memory
PreRender() - the brief moment before the page is displayed to the user as HTML
Unload() - when page finishes loading.
When during the page processing cycle is ViewState available?
After the Init() and before the Page_Load(), or OnLoad() for a control.
What namespace does the Web page belong in the .NET Framework class hierarchy?
System.Web.UI.Page
Where do you store the information about the user’s locale?
System.Web.UI.Page.Culture
What’s the difference between Codebehind="MyCode.aspx.cs" andSrc="MyCode.aspx.cs"?
CodeBehind is relevant to Visual Studio.NET only.
What’s a bubbled event?
When you have a complex control, like DataGrid, writing an event processing routine for each object (cell, button, row, etc.) is quite tedious. The controls can bubble up their eventhandlers, allowing the main DataGrid event handler to take care of its constituents.
Suppose you want a certain ASP.NET function executed on MouseOver for a certain button. Where do you add an event handler?
Add an OnMouseOver attribute to the button. Example: btnSubmit.Attributes.Add("onmouseover","someClientCodeHere();");
What data types do the RangeValidator control support?
Integer, String, and Date.
Explain the differences between Server-side and Client-side code?
Server-side code executes on the server. Client-side code executes in the client's browser.
What type of code (server or client) is found in a Code-Behind class?
The answer is server-side code since code-behind is executed on the server. However, during the code-behind's execution on the server, it can render client-side code such as JavaScript to be processed in the clients browser. But just to be clear, code-behind executes on the server, thus making it server-side code.
Should user input data validation occur server-side or client-side? Why?
All user input data validation should occur on the server at a minimum. Additionally, client-side validation can be performed where deemed appropriate and feasable to provide a richer, more responsive experience for the user.
What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other?
Server.Transfer transfers page processing from one page directly to the next page without making a round-trip back to the client's browser. This provides a faster response with a little less overhead on the server. Server.Transfer does not update the clients url history list or current url. Response.Redirect is used to redirect the user's browser to another page or site. This performas a trip back to the client where the client's browser is redirected to the new page. The user's browser history list is updated to reflect the new address.
Can you explain the difference between an ADO.NET Dataset and an ADO Recordset?
Valid answers are:
· A DataSet can represent an entire relational database in memory, complete with tables, relations, and views.
· A DataSet is designed to work without any continuing connection to the original data source.
· Data in a DataSet is bulk-loaded, rather than being loaded on demand.
· There's no concept of cursor types in a DataSet.
· DataSets have no current record pointer You can use For Each loops to move through the data.
· You can store many edits in a DataSet, and write them to the original data source in a single operation.
· Though the DataSet is universal, other objects in ADO.NET come in different versions for different data sources.
What is the Global.asax used for?
The Global.asax (including the Global.asax.cs file) is used to implement application and session level events.
What are the Application_Start and Session_Start subroutines used for?
This is where you can set the specific variables for the Application and Session objects.
Can you explain what inheritance is and an example of when you might use it?
When you want to inherit (use the functionality of) another class. Example: With a base class named Employee, a Manager class could be derived from the Employee base class.
Whats an assembly?
Assemblies are the building blocks of the .NET framework.
Describe the difference between inline and code behind.
Inline code written along side the html in a page. Code-behind is code written in a separate file and referenced by the .aspx page.
Explain what a diffgram is, and a good use for one?
The DiffGram is one of the two XML formats that you can use to render DataSet object contents to XML. A good use is reading database data to an XML file to be sent to a Web Service.
Whats MSIL, and why should my developers need an appreciation of it if at all?
MSIL is the Microsoft Intermediate Language. All .NET compatible languages will get converted to MSIL. MSIL also allows the .NET Framework to JIT compile the assembly on the installed computer.
Which method do you invoke on the DataAdapter control to load your generated dataset with data?
The Fill() method.
Can you edit data in the Repeater control?
No, it just reads the information from its data source.
Which template must you provide, in order to display data in a Repeater control?
ItemTemplate.
How can you provide an alternating color scheme in a Repeater control?
Use the AlternatingItemTemplate.
What property must you set, and what method must you call in your code, in order to bind the data from a data source to the Repeater control?
You must set the DataSource property and call the DataBind method.
What base class do all Web Forms inherit from?
The Page class.
Name two properties common in every validation control?
ControlToValidate property and Text property.
Which property on a Combo Box do you set with a column name, prior to setting the DataSource, to display data in the combo box?
DataTextField property.
Which control would you use if you needed to make sure the values in two different controls matched?
CompareValidator control.
How many classes can a single .NET DLL contain?
It can contain many classes.

Web Service Questions

What is the transport protocol you use to call a Web service?
SOAP (Simple Object Access Protocol) is the preferred protocol.
True or False: A Web service can only be written in .NET?
False
What does WSDL stand for?
Web Services Description Language.
Where on the Internet would you look for Web services?
from uddi.org
True or False: To test a Web service you must create a Windows application or Web application to consume this service?
False, the web service comes with a test page and it provides HTTP-GET method to test.

State Management Questions

What is ViewState?
ViewState allows the state of objects (serializable) to be stored in a hidden field on the page. ViewState is transported to the client and back to the server, and is not stored on the server or any other external source. ViewState is used the retain the state of server-side objects between postabacks.
What is the lifespan for items stored in ViewState?
Item stored in ViewState exist for the life of the current page. This includes postbacks (to the same page).
What does the "EnableViewState" property do? Why would I want it on or off?
It allows the page to save the users input on a form across postbacks. It saves the server-side values for a given control into ViewState, which is stored as a hidden value on the page before sending the page to the clients browser. When the page is posted back to the server the server control is recreated with the state stored in viewstate.
What are the different types of Session state management options available with ASP.NET?
ASP.NET provides In-Process and Out-of-Process state management. In-Process stores the session in memory on the web server. This requires the a "sticky-server" (or no load-balancing) so that the user is always reconnected to the same web server. Out-of-Process Session state management stores data in an external data source. The external data source may be either a SQL Server or a State Server service. Out-of-Process state management requires that all objects stored in session are serializable.