Types of exception in c#

A C# exception is a response to an exceptional circumstance that arises while a program is running, such as an attempt to divide by zero. Exceptions provide a way to transfer control from one part of a program to another.

C# exception handling is built upon four keywords: try, catch, finally, and throw.

• try: A try block identifies a block of code for which particular exceptions is activated. It is followed by one or more catch blocks.

• catch: A program catches an exception with an exception handler at the place in a program where you want to handle the problem. The catch keyword indicates the catching of an exception.

• finally: The finally block is used to execute a given set of statements, whether an exception is thrown or not thrown. For example, if you open a file, it must be closed whether an exception is raised or not.

• throw: A program throws an exception when a problem shows up. This is done using a throw keyword.

Types of Exceptions in C#

Exception Class	Description
System.IO.IOException	Handles I/O errors.
System.IndexOutOfRangeException	Handles errors generated when a method refers to an array index out of range.
System.ArrayTypeMismatchException	Handles errors generated when type is mismatched with the array type.
System.NullReferenceException	Handles errors generated from deferencing a null object.
System.DivideByZeroException	Handles errors generated from dividing a dividend with zero.
System.InvalidCastException	Handles errors generated during typecasting.
System.OutOfMemoryException	Handles errors generated from insufficient free memory.
System.StackOverflowException	Handles errors generated from stack overflow.

How to extract back up file?

To manually extract files

1. Open the Command Prompt window by clicking the Start button.
   In the search box, type Command Prompt, and then, in the list of results, click Command Prompt.
  
2. Type the following command:
C:\Users\Nagasai\Downloads>copy "Send_file_test.bak" “Send_file_test.mdb”

Hope this helps!!!

How to Kill Excel Ghost Process in SSIS using VB.NET

Here is the simple method to kill Excel Ghost process which is running behind scene while running SSIS package. Here is a small method to kill Excel process if we know the excel caption or excel title we want to close.
Code snippet of the method to kill Excel process

Private Sub KillExcellProcess(ByVal excelCaption As String)
    Dim proc As System.Diagnostics.Process
    For Each proc In System.Diagnostics.Process.GetProcessesByName("EXCEL")
        If (proc.MainWindowTitle = excelCaption) Then
            proc.Kill()
        End If
    Next
End Sub

Use this method in SSIS script task to kill the Excel Ghost process by calling this method in your code

 

Dim xlApp As Excel.Application
Dim xlBook As Excel.WorkbookClass
xlApp = CType(CreateObject("Excel.Application"), Excel.Application)
xlApp.Visible = False
xlApp.DisplayAlerts = False
' Once done with excel stuff and when you want 
' to kill excel use the below lines of code
Dim sCaption As String
sCaption = xlApp.Caption
KillExcellProcess(sCaption)

 

Hope this helps!!

How to Kill specific Excel Ghost Process generated in SSIS using VB.NET

There are some scenarios where we might need to kill excel process programmatically.  Even though we use proper error handling and try catch to clear all excel objects still the excel ghost process remains in usage. So for these cases we might need to kill the excel process generated in SSIS package by identifying its process.   Here is how we can kill specific excel process by getting the process id of the excel that is been generated by SSIS package in script task. Refer to my previous blog for kill process by its name

<Runtime.InteropServices.DllImport("user32.dll")> _
 Private Shared Function EndTask(ByVal hWnd As System.IntPtr) As Integer
 End Function
<Runtime.InteropServices.DllImport("user32.dll")> _
 Private Shared Function FindWindow(ByVal lpClassName As String, ByVal lpWindowName As String) As IntPtr
 End Function
<Runtime.InteropServices.DllImport("kernel32.dll")> _
 Private Shared Function SetLastError(ByVal dwErrCode As Integer) As IntPtr
 End Function
<Runtime.InteropServices.DllImport("user32.dll", SetLastError:=True)> _
 Private Shared Function GetWindowThreadProcessId(ByVal hWnd As System.IntPtr, ByRef lpdwProcessId As Integer) As Integer
 End Function

 Public Sub EnsureProcessKilled(ByVal MainWindowHandle As System.IntPtr, ByVal Caption As String)
     SetLastError(0)
   ' for Excel versions <10, this won't be set yet
     If System.IntPtr.Equals(MainWindowHandle, System.IntPtr.Zero) Then
       MainWindowHandle = FindWindow(Nothing, Caption)
     End If
     If System.IntPtr.Equals(MainWindowHandle, System.IntPtr.Zero) Then
         Return
     End If
     ' at this point, presume the window has been closed.
     Dim iRes As Integer = 0
     Dim iProcID As Integer = 0
     iRes = GetWindowThreadProcessId(MainWindowHandle, iProcID)
     ' can?t get Process ID
     If iProcID = 0 Then
        If EndTask(MainWindowHandle) <> 0 Then
             Return
         End If
         ' success
         Throw New ApplicationException("Failed to close.")
     End If
     Dim proc As System.Diagnostics.Process = Nothing
     proc = System.Diagnostics.Process.GetProcessById(iProcID)
     proc.CloseMainWindow()
     proc.Refresh()
     If proc.HasExited Then
         Return
     End If
     proc.Kill()
 End Sub

Use this method in SSIS script task to kill the Excel Ghost process by calling this method in your code

 

Dim sVer As String
sVer = xlApp.Version
Dim iHandle As IntPtr = IntPtr.Zero
If Val(Convert.ToDouble(sVer)) >= 10.0 Then
 iHandle = New IntPtr(CType(xlApp.Parent.Hwnd, Integer))
End If
'To kill process created by this job by process id
EnsureProcessKilled(iHandle, xlApp.Caption)

Hope this help!!

SMTP Server Error: Bad sequence of commands. The server response was: you must authenticate first (#5.5.1)

This error occurs due to lock down of default mail server (127.0.0.1) by web hosting companies due to SPAM or what ever other security reasons. But if you use “localhost” or default server “127.0.0.1” on your local machine it should not be an issue. But if you have a situation where you need to relay e-mail to a remote mail server that is secured you get this exception.

So you need to handle well using built in classes provided by .NET. This is take care by NetworkCredential Class. This class provides credentials for password-based authentication schemes such as basic, digest, NTLM, and Kerberos authentication.

Here is a fully working quick code sample that you can use to get started on your own SMTP-Authentication supporting e-mail code.

   1: try

   2: {

   3:     SmtpClient smtpclient = new SmtpClient();

   4:     NetworkCredential NetworkCredential = new NetworkCredential(smtpUserName, smtpPassword);

   5:     smtpclient.Credentials = NetworkCredential;

   6:     string MailServer = ConfigurationManager.AppSettings["SMTPServer"].ToString();

   7:     MailMessage objEmail = new MailMessage();

   8:  

   9:     string FromEmail = ConfigurationManager.AppSettings["ErrorReportEmailFrom"].ToString();

  10:     if (FromEmail.IndexOf(";") > 0)

  11:     {

  12:         FromEmail = FromEmail.Replace(";", ",");

  13:     }

  14:     MailAddress FromAddress = new MailAddress(FromEmail);

  15:     objEmail.From = FromAddress;

  16:  

  17:     string ToEmail = ConfigurationManager.AppSettings["ErrorReportEmailTo"].ToString();

  18:     if (ToEmail.IndexOf(";") > 0)

  19:     {

  20:         ToEmail = ToEmail.Replace(";", ",");

  21:     }

  22:     objEmail.To.Add(ToEmail);

  23:  

  24:     string CcEmail = ConfigurationManager.AppSettings["CcEmail"].ToString();

  25:     if (CcEmail.IndexOf(";") > 0)

  26:     {

  27:         CcEmail = CcEmail.Replace(";", ",");

  28:     }

  29:     objEmail.CC.Add(CcEmail);

  30:  

  31:     string BccEmail = ConfigurationManager.AppSettings["BccEmail"].ToString();

  32:     if (BccEmail.IndexOf(";") > 0)

  33:     {

  34:         BccEmail = BccEmail.Replace(";", ",");

  35:     }

  36:     objEmail.Bcc.Add(BccEmail);

  37:  

  38:     objEmail.Subject = strSubject;

  39:     try

  40:     {

  41:         objEmail.Body = strBody;

  42:         objEmail.IsBodyHtml = true;

  43:         smtpclient.Host = MailServer;

  44:         smtpclient.Send(objEmail);

  45:     }

  46:     catch (Exception ex)

  47:     {

  48:         throw ex;

  49:     }

  50:     finally

  51:     {

  52:         objEmail.Dispose();

  53:     }

  54: }

  55: catch (Exception ex)

  56: {

  57:      

  58: }

Enjoy coding!!

How to Set default button from C# to a Content Page

Here is how we can use default button property of the form to set Default Button for a content page from Code behind using C#

 

// Setting default button
this.Master.Page.Form.DefaultButton = this.btnSubmit.UniqueID;

 

Here is how we can set default button for the page which doesn’t have Master Page

// Setting Default Button           
this.Page.Form.DefaultButton = btnSubmit.UniqueID; 

 

Hope this helps!!

How to get Line break in a button using HTML and CSS

Some times there are some scenarios where we might put some line breaks in buttons while doing HTML code your pages. There are few different ways that you can achieve this using HTML and CSS.

Here are few code snippets

   1: <!-- Method 1 -->

   2: <input type='submit' value='my \n button'>

   3: <!-- Method 2 Using HTML break-->

   4: <input type='submit' value='my &lt;br> button'> 

   5: <!-- Method 3: Using CSS -->

   6: <input type="submit" value="My button" style="white-space:normal"/>

Hope this helps!!

How to: String to Pascal case from C#

We can return a string to Pascal case using regular expression or using our own logic. Here are two scenarios for doing this.

Method 1: Regular expression

public static string ToPascalCase(string pascalCaseString)
{
    Regex r = new Regex("(?<=[a-z])(?<x>[A-Z])|(?<=.)(?<x>[A-Z])(?=[a-z])");
    return r.Replace(pascalCaseString, " ${x}");
}

Method 2: String parsing.

/// <summary>
/// Convert the string to Pascal case.
/// </summary>
/// <param name="str">the string to turn into Pascal case</param>
/// <returns>a string formatted as Pascal case</returns>
public static string FormatPascalCase(string str)
{
    StringBuilder sb = new StringBuilder(str.Length);
    if (string.IsNullOrEmpty(str))
        throw new ArgumentException("A null or empty value cannot be converted", str);

    if (str.Length < 2)
        return str.ToUpper();
    // Split the string into words.
    string[] words = str.Split(new char[] { }, StringSplitOptions.RemoveEmptyEntries);
    foreach (string word in words)
        sb.Append(string.Format("{0}{1}", word.Substring(0, 1).ToUpper(), word.Substring(1)));
    return sb.ToString();
}

Hope this helps.

How to: change DB owner name using T-SQL

Here is how you can do it using SQL Statement.

Method 1:

Using this method first we’ll get all the db objects and update with new db owner name.

DECLARE tabcurs CURSOR
FOR
    SELECT 'olddbowner.' + [name]
      FROM sysobjects
     WHERE xtype = 'u'

OPEN tabcurs
DECLARE @tname NVARCHAR(517)
FETCH NEXT FROM tabcurs INTO @tname

WHILE @@fetch_status = 0
BEGIN

    EXEC sp_changeobjectowner @tname, 'dbo'

    FETCH NEXT FROM tabcurs INTO @tname
END
CLOSE tabcurs
DEALLOCATE tabcurs

Method 2:

This approach is simple and straight forward. Using this we will build the statements and you can copy them from the result window and execute

declare @OldOwner varchar(100) declare @NewOwner varchar(100) 
set @OldOwner = '353446_eda_db' 
set @NewOwner = 'dbo' 


SELECT 'sp_changeobjectowner ''[' + s.name + '].[' + p.name + ']'', ''' + @NewOwner + '''
 GO'
FROm sys.Procedures p INNER JOIN 
sys.Schemas s on p.schema_id = s.schema_id WHERE s.Name = @OldOwner
union
select 'sp_changeobjectowner ''[' + table_schema + '].[' + table_name + ']'', ''' + @NewOwner + '''
 GO'
 from information_schema.tables where Table_schema = @OldOwner

Hope this helps.

Regex validate Email address C#

This is how we can validating email address through C# using Regular Expression. Here is the sample code,

using System.Text.RegularExpressions;

public bool vaildateEmail(string useremail)
{
    bool istrue = false;
    Regex reNum = new Regex(@"\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*");
    CaptureCollection cc = reNum.Match(useremail).Captures;
    if (cc.Count == 1)
    {
        istrue = true;
    }
    return istrue;
}

Delete All Files using C#

For Deleting all the files first you need to get the list of file names from the specified directory (using static method Directory.Get­Files. Then delete all files from the list.

Method 1

using System.IO;

string[] filePaths = Directory.GetFiles(@"c:\Directory\");
foreach (string filePath in filePaths)
  File.Delete(filePath)

Method 2

To Delete all files using one code line, you can use Array.ForEach with combination of anonymous method.

Array.ForEach(Directory.GetFiles(@"c:\MyDirectory\"),delegate(string path) 
{ File.Delete(path); });

How to get current page Filename using C#

There are different ways to get current page filename using c#. Here are 3 methods you can use for your advantage.

Method 1

string currentPageFileName = new FileInfo(this.Request.Url.LocalPath).Name;

Method 2

string sPath = HttpContext.Current.Request.Url.AbsolutePath;
string[] strarry = sPath.Split('/');
int lengh = strarry.Length;
string sReturnPage = strarry[lengh - 1];

Method 3

string absPath = System.Web.HttpContext.Current.Request.Url.AbsolutePath;
System.IO.FileInfo finfo = new System.IO.FileInfo(absPath);
string fileName = finfo.Name;

 

Out of these I like Method 1 and 3 as its straight forward. Use a per your advantage. Good luck.

C# Checking a File exists in Folder

How to get all files from a folder and compare a whether that file exists in that folder or not. Here is a sample code where you can loop through the code and check the file.

I have declared a variable to check there it exists or not.

private bool isFileExists = false;

Now I have this code to check whether file exists and based on it I’ll redirect in to that page.

string searchfolder = Server.MapPath("~") + "\\TestFolder";
DirectoryInfo Dir = new DirectoryInfo(searchfolder);
FileInfo[] FileList = Dir.GetFiles("*.aspx", SearchOption.AllDirectories);
foreach (FileInfo FI in FileList)
{
    if (FI.Name == redirectPage)
    {                            
        isFileExists = true;
        break;
    }                       
}
if (isFileExists == true)
{
    Response.Redirect("~/redirectPage");
}
else
{
    Response.Redirect("~/OtherRedirect.aspx");
}

Here I have search pattern as *.aspx as I need to check these files. This can be based on the files you want to check

Convert DateTime values to W3C DateTime format in C#

ConvertDateToW3CTime() function takes a C# DateTime value and converts it to a W3C formatted date/time value.
The function works by first converting the date/time parameter to a UTC (Coordinated Universal Time) value and formatting it. It then appends the UTC offset time to the previously formatted string.

The T placed between the date and time simply indicates that the numbers following it are Time values. The UTC offset can be one 3 states, zero e.g. there is not difference in time between the UTC value and the local value. A zero value is identified by simply appending the letter Z to the end of the formatted datetime value. If the offset time is greater than 0 then it is preceded with a + sign, e.g. 2 hours and 30 minutes over the UTC time would be written as +02:30. If the offset is less than the UTC value then it is preceded with a – sign e.g. -01:00.

/// <summary>
/// Converts a datetime value to w3c format
/// </summary>
/// <param name="date"></param>
/// <returns></returns>
public static string ConvertDateToW3CTime(DateTime date)
{
    //Get the utc offset from the date value
    var utcOffset = TimeZone.CurrentTimeZone.GetUtcOffset(date); 
    string w3CTime = date.ToUniversalTime().ToString("yyyy-MM-ddTHH:mm:ss");
    //append the offset e.g. z=0, add 1 hour is +01:00
    w3CTime += utcOffset == TimeSpan.Zero ? "Z" :
        String.Format("{0}{1:00}:{2:00}", (utcOffset > TimeSpan.Zero ? "+" : "-")
        , utcOffset.Hours, utcOffset.Minutes);
 
    return w3CTime;
}

Here is an example, how to use it

ConvertDateToW3CTime(DateTime.Now);
//Output 2011-10-17T19:10:48+01:00

How to Add validations controls Programmatically

I was looking for some server side validation message which can done without posting back to server. I tried doing javascript and writing that script to literal control and I have been thinking of doing a better way. But here is the cool way to do this.

// Dynamically adding Validation control
RequiredFieldValidator Validator = new RequiredFieldValidator();
Validator.ErrorMessage = "No data to download for your request.";
// Validation group must be specified as to which group you need to bind
Validator.ValidationGroup = "Group1";
Validator.IsValid = false;
Validator.Visible = false;
Page.Form.Controls.Add(Validator);   

All you need to do is Depending on your need you need to change message and validation group. We need to set up validation group properly.

Happy coding

Microsoft Code Samples for Developers

This code sample library will help all developers to find useful code in various dot net areas. Microsoft goal is to centralized all codes in one place. This library having below things:

• Microsoft All-in-One Code Framework: Free, centralized code sample library
  • Code Samples
  • Services
• Microsoft SDKs: provide documentation, code samples, tools etc..
• MSDN Code Gallery:  download and share sample applications, code snippets and other resources.

You can download it from here

Clear Browser History Through Javascript

If you need to clear the Browser History, after arriving on a particular page (e.g. arriving to Login page after Logout).

Here is the code to do this. If you put this code in Login page, it wont take it to be back page. You need to put this from where you do not want to move back. Here is the code snippet.

<script type="text/javascript">
        window.onload = function () { Clear(); }
        function Clear() {            
            var Backlen = history.length;
            if (Backlen > 0) history.go(-Backlen);
        }
</script>

if you do not want the user to move to the back page, you can do as below. This script needs to be repeated at where you don’t want to do this.

<script type="text/javascript">
       if(window.history.forward(1) != null)
           window.history.forward(1);
</script>

Hope this helps.

Date Formatting in C#

Date formatting in C# using string object

Specifier	Description	Output
d	Short Date	20/10/1983
D	Long Date	20 October 1983
t	Short Time	21:20
T	Long Time	21:20:59
f	Full date and time	20 October 1983 21:20
F	Full date and time (long)	20 October 1983 21:20:59
g	Default date and time	20/10/1983 21:20
G	Default date and time (long)	20/10/1983 21:20:59
M	Day / Month	20 October
r	RFC1123 date	Thu, 20 Apr 1983 21:20:59 GMT
s	Sortable date/time	1983-10-20T21:20:59
u	Universal time, local timezone	1983-10-20 21:20:59Z
Y	Month / Year	October 1983
dd	Day	20
ddd	Short Day Name	Thu
dddd	Full Day Name	Thursday
hh	2 digit hour	09
HH	2 digit hour (24 hour)	21
mm	2 digit minute	20
MM	Month	10
MMM	Short Month name	Apr
MMMM	Month name	October
ss	seconds	59
tt	AM/PM	PM
yy	2 digit year	07
yyyy	4 digit year	1983
:	seperator, e.g. {0:hh:mm:ss}	09:20:59
/	seperator, e.g. {0:dd/MM/yyyy}	20/10/1983

Example using the specifier with data object

DateTime now = DateTime.Now;
Console.WriteLine(now.ToString("d"));

JavaScript: Display Clock

Displaying a clock is very similar to making a countdown timer. All we have to do is to create a new date and get it's hours, minutes, and seconds.

Here is a example:

<!-- This span is where the clock will appear -->
<div id='clockDiv'></div>
<script type="text/javascript">
function clock() {
   var now = new Date();
   var outStr = now.getHours()+':'+now.getMinutes()+':'+now.getSeconds();
   document.getElementById('clockDiv').innerHTML=outStr;
   setTimeout('clock()',1000);
}
clock();
</script>

Hope this helps :-)

JavaScript: Count down Timer

This is how creating Count down timer using JavaScript with Julian dates. This code below creates two Julian dates, now and newYear. By subtracting now from newYear we get an integer which represents the difference between the two dates.

Suppose you want to know your birthday in days, hours and minutes etc. This is how you can achieve using JavaScript.

<!-- This span is where the countdown timer will appear -->
<div id='countdown'></div>
<script type="text/javascript">
// Here's our countdown function.
function happyBirthDay() {
var now = new Date();
var newYear = new Date('October 20, '+(now.getFullYear()+1));
var diff=newYear-now;
var milliseconds=Math.floor(diff % 1000);   
    diff=diff/1000;            
var seconds=Math.floor(diff % 60);
    diff=diff/60;
var minutes=Math.floor(diff % 60);
    diff=diff/60;
var hours=Math.floor(diff % 24);
    diff=diff/24;
var days=Math.floor(diff);
// We'll build a display string instead of doing document.writeln
   var outStr = days + ' days, ' + hours+ ' hours, ' + minutes;
       outStr+= ' minutes, ' + seconds + ' seconds until your birthday!'; 
   // Insert our display string into the countdown span.
   document.getElementById('countdown').innerHTML=outStr;
   // call this function again in exactly 1 second.   
   setTimeout("happyBirthDay()",1000);
}
// call the countdown function (will start the timer)
happyBirthDay();   
</script>

Hope this helps!