How to sort Rows/Data in a DataTable

We can sort binding source, data view and data table default view to sort data in a data table. There are following three methods which can be applied:

Method 1:
 bindingSource.DataSource = table
 dataGridView.DataSource = bindingSource
 bindingSource.Sort = "Column_Name"

Method 2:
Alternatively, you can just use a DataView:

 Dim view as DataView = new DataView(table)
 view.Sort = "Column_Name"
 dataGridView.DataSource = view

Method 3:
or change the DataTable's DefaultView:

 table.DefaultView.Sort = "Column_Name"

Column_Name is the name of one or more columns on which a sort is required. So a Column_Name can have following values like: "COUNTRY" or "COUNTRY, POPULATION" or "COUNTRY, POPULATION DESC".

.NET Framework Value Types and Reference Types

Value Types:
The .NET Framework includes a large number of built-in types that you can use directly or use to build your own custom types.

Value types directly contain their data, offering excellent performance. However, value types are limited to types that store very small pieces of data. In the .NET Framework, all value types are 16 bytes or shorter.

You can create user-defined types that store multiple values and methods. In object-oriented development environments, a large portion of your application logic will be stored in user-defined types.

Enumerations improve code readability by providing symbols for a set of values.

Reference Types:
Reference types contain the address of data rather than the actual data.

When you copy a value type, a second copy of the value is created. When you copy a reference type, only the pointer is copied. Therefore, if you copy a reference type and then modify the copy, both the copy and the original variables are changed.

The .NET Framework includes a large number of built-in reference types that you can use directly or use to build your own custom types.

Strings are immutable; use the StringBuilder class to create a string dynamically.

Use streams to read from and write to files, memory, and the network.

Use the Catch clause within Try blocks to filter exceptions by type. Close and dispose of nonmemory resources in the Finally clause of a Try block.

VB.Net Draw String Center of Point location

Private Sub DrawStringCenterOfPoint(ByRef gr As Graphics, _
                ByVal txt As String, ByVal txtfont As Font, _
                  ByVal txtcolor As Brush, ByVal location As PointF)

     ' Mark the center for debugging
     Dim x as Single = location.X
     Dim y as Single = location.Y
     gr.DrawLine(New Pen(Color.Red, 2), x - 10, y, x + 10, y)
     
     ' Make a StringFormat object that centers
     Dim sf As New StringFormat
     sf.LineAlignment = StringAlignment.Center
     sf.Alignment = StringAlignment.Center

     ' Draw the text.
     Dim StringSize As New SizeF
     StringSize = gr.MeasureString(txt, txtfont)

     gr.DrawString(txt, txtfont, txtcolor, x, y, sf)
     sf.Dispose()

End Sub

VB.Net Find Center of a Polygon

Private Function CenterOfPolygon(ByRef _pointf() As PointF) As PointF
     CenterOfPolygon = New Point(0, 0)

     Dim total_points As Integer = _pointf.Length
     Dim x_total As Single = 0, y_total As Single = 0
     For Each _point As PointF In _pointf
         x_total = x_total + _point.X
         y_total = y_total + _point.Y
     Next

     CenterOfPolygon.X = x_total / total_points
     CenterOfPolygon.Y = y_total / total_points

End Function

Microsoft .Net - Value Types and Reference Types

A data type is a value type if it holds the data within its own memory allocation. A reference type contains a pointer to another memory location that holds the data.

Value Types

Value types include the following:

· All numeric data types

· Boolean, Char, and Date

· All structures, even if their members are reference types

· Enumerations, since their underlying type is always SByte, Short, Integer, Long, Byte, UShort, UInteger, or ULong

Reference Types

Reference types include the following:

· String

· All arrays, even if their elements are value types

· Class types, such as Form

· Delegates

Elements That Are Not Types

The following programming elements do not qualify as types, because you cannot specify any of them as a data type for a declared element:

· Namespaces

· Modules

· Events

· Properties and procedures

· Variables, constants, and fields

Working with the Object Data Type

You can assign either a reference type or a value type to a variable of the ObjectObject variable always holds a pointer to the data, never the data itself. However, if you assign a value type to an Object variable, it behaves as if it holds its own data. For more information, see data type. An Object Data Type.

You can find out whether an Object variable is acting as a reference type or a value type by passing it to the IsReference method on the Information class in the Microsoft.VisualBasic namespace. Microsoft.VisualBasic.Information.IsReference(System.Object) returns TrueObject variable represents a reference type. if the content of the

Microsoft. Net - Replace BitMap Color

Private Function ReplaceBitMapColor(ByVal originalBMP As Bitmap, _
                                           ByVal oldColor As Color, _
                                               ByVal newColor As Color) As Bitmap
 Dim image As New Bitmap(originalBMP)
 Dim graphics As Graphics = Graphics.FromImage(image)
 Dim map As ColorMap() = New ColorMap() {New ColorMap}
 map(0).OldColor = oldColor
 map(0).NewColor = newColor

 Dim imageAttr As New ImageAttributes
 imageAttr.SetRemapTable(map)

 Dim destRect As New Rectangle(0, 0, image.Width, image.Height)
 graphics.DrawImage(image, destRect, 0, 0, _
                       image.Width, image.Height, _
                           GraphicsUnit.Pixel, imageAttr)

 Return image

End Function

VB.Net - Export DataTable to CSV

Public Sub ExportDataTableToCSV(ByRef dtSource As DataTable, _
                     ByVal filename As String)

   Dim context As HttpContext = HttpContext.Current
   context.Response.Clear()
   For Each column As DataColumn In dtSource.Columns
       context.Response.Write(column.ColumnName + ",")
   Next
   context.Response.Write(Environment.NewLine)

   For Each row As DataRow In dtSource.Rows
       For i As Integer = 0 To dtSource.Columns.Count - 1
          context.Response.Write(row(i).ToString().Replace(",", String.Empty) + ",")
       Next
     context.Response.Write(Environment.NewLine)
   Next

   context.Response.ContentType = "text/csv"
   context.Response.AppendHeader("Content-Disposition", _
                         "attachment; filename=" + filename + ".csv")
   context.Response.End()

End Sub

VB.Net - Get Week Number of a date

Public Function GetWeekNumber(ByVal inDate As DateTime) As Integer
     Const JAN As Integer = 1
     Const DEC As Integer = 12
     Const LASTDAYOFDEC As Integer = 31
     Const FIRSTDAYOFJAN As Integer = 1
     Const THURSDAY As Integer = 4
     Dim ThursdayFlag As Boolean = False

     ' Get the day number since the beginning of the year
     Dim DayOfYear As Integer = inDate.DayOfYear

     ' Get the numeric weekday of the first day of the
     ' year (using sunday as FirstDay)
     Dim StartWeekDayOfYear As Integer = _
     DirectCast(New DateTime(inDate.Year, JAN, FIRSTDAYOFJAN).DayOfWeek, Integer)
     Dim EndWeekDayOfYear As Integer = _
     DirectCast(New DateTime(inDate.Year, DEC, LASTDAYOFDEC).DayOfWeek, Integer)

    ' Compensate for the fact that we are using monday
    ' as the first day of the week
    If StartWeekDayOfYear = 0 Then
       StartWeekDayOfYear = 7
    End If
    If EndWeekDayOfYear = 0 Then
       EndWeekDayOfYear = 7
    End If

    ' Calculate the number of days in the first and last week
    Dim DaysInFirstWeek As Integer = 8 - StartWeekDayOfYear
    Dim DaysInLastWeek As Integer = 8 - EndWeekDayOfYear

    ' If the year either starts or ends on a thursday it will have a 53rd week
    If StartWeekDayOfYear = THURSDAY OrElse EndWeekDayOfYear = THURSDAY Then
        ThursdayFlag = True
    End If

    ' We begin by calculating the number of FULL weeks
    ' between the start of the year and
    ' our date. The number is rounded up, so the smallest possible value is 0.
    Dim FullWeeks As Integer = _
        CType(Math.Ceiling((DayOfYear - DaysInFirstWeek) / 7), Integer)

    Dim WeekNumber As Integer = FullWeeks

    ' If the first week of the year has at least four days,
    ' then the actual week number for our date
    ' can be incremented by one.
    If DaysInFirstWeek >= THURSDAY Then
        WeekNumber = WeekNumber + 1
    End If

    ' If week number is larger than week 52
    ' (and the year doesn't either start or end on a thursday)
    ' then the correct week number is 1.
    If WeekNumber > 52 AndAlso Not ThursdayFlag Then
        WeekNumber = 1
    End If

    ' If week number is still 0,
    ' it means that we are trying to evaluate the week number for a
    ' week that belongs in the previous year
    ' (since that week has 3 days or less in our date's year).
    ' We therefore make a recursive call using the last day of the previous year.
    If WeekNumber = 0 Then
        WeekNumber = GetWeekNumber( _
            New DateTime(inDate.Year - 1, DEC, LASTDAYOFDEC))
    End If

    Return WeekNumber
End Function

VB.Net - Get Weeks In a Year

Public Function GetWeeksInYear(ByVal dayofsunday As DateTime) As Integer

     Dim dayofthursday As DateTime = dayofsunday.AddDays(-3)
     Dim yearno As Integer = dayofthursday.Year
     Dim firstday As DateTime = "01-Jan-" & yearno.ToString

     Dim totalweeks As Integer = 0

     If firstday.DayOfWeek = DayOfWeek.Thursday Then
         totalweeks = 53
     ElseIf Date.IsLeapYear(yearno) = True _
              And firstday.DayOfWeek = DayOfWeek.Wednesday Then
         totalweeks = 53
     Else
         totalweeks = 52
     End If

     Return totalweeks
End Function

VB.Net - Get Directory / Folder Size

Public Function GetFolderSize(ByVal path As String, _
                ByVal includeSubFolders As Boolean) As Long

     GetFolderSize = 0

     Dim main_dir As New System.IO.DirectoryInfo(path)
     Dim dir_files() As FileInfo

     If includeSubFolders Then
         dir_files = main_dir.GetFiles("*", SearchOption.AllDirectories)
     Else
         dir_files = main_dir.GetFiles("*", SearchOption.TopDirectoryOnly)
     End If

     For Each ofile As IO.FileInfo In dir_files
         GetFolderSize = GetFolderSize + ofile.Length
     Next

End Function

IIS Worker Process and Application Pooling

Web server?
IIS (Internet Information Service) running on a software port like 80 for Http and 443 for Https or any other port set bt the administrator, it can host more than one web site and each web site can hold more than one web application. Web server provides application pooling and hanldes all web request from the internet and forward it to respective web site's application pool for processing and response. IIS can host classic asp applications, asp.net applications, php applications, etc.

Application Pooling?
The Windows IIS web server, has application pools where different web applications or web sites can be pooled. When we say pooled it means it is loaded in the process, so the web requests are processed. Why pooling? becuase the application will handle multiple web requests, the application is loaded once, and remains in the pool for quite some time to process subsequent requests and when remains idel for too long it is unloded. The pooling helps better manage server resources, so the CPU and Memory is not consumed uselessly. An application pool can hold more than one web application, and IIS can have more than one application pools. Application pools it self is comprehensive topic and it provides many things to tune your web application performace.

Worker Process?
As we discussed above, application pooling is done in IIS, Worker Process is actually a program that executes in the system memory for a specific application pool, if we have three application pools and the pools are active than we will have three process running it the system memory, these are the processes which handle the requests and send response. The "w3wp.exe" program can be easily found in the task manager, this is the program running behind the application pool.
We can define more than one worker process in an application pool, by default we have one worker process in an application pool, this means there is only one queue for my web requests, so ten request will execute one at a time.
If i increase the number to 2, so now my application pool has 2 worker process, this means there are two queues for my web requests, so ten request will execute two at a time. Ofcourse the CPU time will be divied between the two worker processes, this means to many worker processes will cut down the overall response time if i have a moderate server, therefore it depends upon the hardware of the server that how many worker processes it can hold.

Microsoft .NET platform

Category	Technologies
Application Infrastructure	Common Language Runtime (CLR) .NET Framework
Mobile	.NET Compact Framework ASP.NET Mobile Silverlight Mobile Web
Web	ASP.NET
Rich Internet Application (RIA)	Microsoft Silverlight
Rich Client	Windows Forms Windows Presentation Foundation (WPF)
Services	ASP.NET Web Services (ASMX) Windows Communication Foundation (WCF)
Collaboration / Integration / Workflow	Windows Workflow Foundation (WF) Microsoft Office SharePoint Server (MOSS) Microsoft BizTalk Server
Web Server	Internet Information Services (IIS)
Database Server	Microsoft SQL Server

Logon Info and Parameter Value for Crystal reports

Imports Microsoft.VisualBasic
Imports System.Data.SqlClient
Imports CrystalDecisions.Shared
Imports CrystalDecisions.CrystalReports.Engine

Public Sub SetLogonInfo(ByRef objrpt As ReportDocument)

  Dim connection As IConnectionInfo
  Dim newServerName As String = "dbServer"
  Dim newDatabaseName As String = "dbName"

  Dim userID As String = "dbusername"
  Dim password As String = "dbpassword"

  ' Change the server name and database in main reports

  For Each connection In objrpt.DataSourceConnections
      ' SetConnection can also be used to set
      ' new logon and new database table
      objrpt.DataSourceConnections(connection.ServerName, _
                      connection.DatabaseName).SetConnection( _
                          newServerName, newDatabaseName, userID, password)
  Next

  ' Change the server name and database in subreports
  Dim subreport As ReportDocument

  For Each subreport In objrpt.Subreports

    For Each connection In subreport.DataSourceConnections

       ' SetConnection can also be used to set
       ' new logon and new database table
       subreport.DataSourceConnections(connection.ServerName, _
               connection.DatabaseName).SetConnection( _
                  newServerName, newDatabaseName, userID, password)
    Next

  Next

End Sub


Public Sub SetParameterValue(ByRef objRPT As ReportDocument, _
                               ByVal parameterName As String, _
                                  ByVal ParameterValue As String)

  Dim parameterField As ParameterField

  parameterField = objRPT.ParameterFields(parameterName)
  parameterField.CurrentValues.AddValue(ParameterValue)
  parameterField.HasCurrentValue = True

End Sub

ASP.Net "Index was outside the bounds of the array" Publish Website Issue

With Visual Studio SP1 when they use the "Publish Website" command with a web project configured to use the built-in ASP.NET Development Web Server with a "/" as the virtual path encounter an "Index was outside the bounds of the array" error message during publishing:



This is a bug as regression in VS 2005 SP1, for this we a public hotfix for the issue that you can directly download here

Failed to access IIS metabase problem

When you install IIS AFTER .NET 2.0 framework, the rights of the ASPNET user had not been set correctly.

Repair (Uninstall if repair does not work for you) .NET Framework 2.0

Simply run the following from command line to reset the IIS registry settings for aspnet user. Usually framework directory for .Net Framework 2.0 resides under C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727

C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis -i

Reference: http://support.microsoft.com/?kbid=267904

On Vista and VS 2005 check the shortcut to VS 2005, and make sure 'Run as Administrator' option is checked. If not check this option in Advance section.

ASP.Net Session State Management

Here i will try to detail the important ASP.Net session state management, my topic will targer Windows server 2003 with IIS6.

Web server?
IIS (Internet Information Service) running on a software port like 80 for Http and 443 for Https or any other port set bt the administrator, it can host more than one web site and each web site can hold more than one web application. Web server provides application pooling and hanldes all web request from the internet and forward it to respective web site's application pool for processing and response. IIS can host classic asp applications, asp.net applications, php applications, etc.

Application Pooling?
The Windows IIS web server, has application pools where different web applications or web sites can be pooled. When we say pooled it means it is loaded in the process, so the web requests are processed. Why pooling? becuase the application will handle multiple web requests, the application is loaded once, and remains in the pool for quite some time to process subsequent requests and when remains idel for too long it is unloded. The pooling helps better manage server resources, so the CPU and Memory is not consumed uselessly. An application pool can hold more than one web application, and IIS can have more than one application pools. Application pools it self is comprehensive topic and it provides many things to tune your web application performace.

Worker Process?
As we discussed above, application pooling is done in IIS, Worker Process is actually a program that executes in the system memory for a specific application pool, if we have three application pools and the pools are active than we will have three process running it the system memory, these are the processes which handle the requests and send response. The "w3wp.exe" program can be easily found in the task manager, this is the program running behind the application pool.
We can define more than one worker process in an application pool, by default we have one worker process in an application pool, this means there is only one queue for my web requests, so ten request will execute one at a time.
If i increase the number to 2, so now my application pool has 2 worker process, this means there are two queues for my web requests, so ten request will execute two at a time. Ofcourse the CPU time will be divied between the two worker processes, this means to many worker processes will cut down the overall response time if i have a moderate server, therefore it depends upon the hardware of the server that how many worker processes it can hold.

Each worker process has its own memory as well, so be carefull while configuring this number.

Now as we have a good background of the web server, application pooling and worker process, we can move forward to our actually topic, that is the Session Sate Management.

What is Session?
HTTP is a stateless protocol. Each request is serviced as it comes; after the request is processed, all of the data is discarded. No state is maintained across requests even from the same client.
However, it is very useful to maintain state across requests for certain solutions. ASP.NET enables you to maintain both application state and session state through use of application and session variables respectively.
Session is a way of persisting or storing client data on web server between subsequent request from the client. Here client is the browser or internet browsing application which is making requests to our web server.
Web server can host different web sites, each web site can maintain its own sessions, regardless of the web server. Sessions are maintained for sites, like we would want to track the users shopping cart temporarily until the user checks out, this can be done in the session of the client.
Sessions are stored in the system memory of the web server, and the memory is allocated by the "w3wp.exe" worker process program. Information stored in client session dont lose unless the session is destroyed on the server or the user signs out. We have timeout set for sessions, default is 20 minutes, if a session remains idle for more than 20 minutes it is automatically destroyed, this is becuase there is no user interaction, so the session remained inactive. As sessions are created it consumes system memory, and when sessions are destroyed the system memory is released. Session variables are automatically discarded after they are not used for the time-out setting that is specified in the Web.config file. On each request, the time out is reset. The variables are lost when the session is explicitly abandoned in the code.

Session ID:
When a session is initiated on first request, the server issues a unique session ID to the user. To persist the session ID, store it in an in-memory cookie (which is the default), or embed it within the request URL after the application name. To switch between cookie and cookieless session state, set the value of the cookieless parameter in the Web.config file to true or false.

1. Cookieless
2. Cookie

In cookieless mode, the server automatically inserts the session ID in the relative URLs only. An absolute URL is not modified, even if it points to the same ASP.NET application, which can cause the loss of session variables.

Session State:
Now what is session state, and why i am highlighting it? because knowning what is session is not enough, Asp.Net provides different ways to manager session state according to the requirements of the web applications. We can store session in following, this is configured through web configuration file of a web application:

InProc or Worker Process: In-Proc mode stores values in the memory of the ASP.NET worker process. Thus, this mode offers the fastest access to these values. However, when the ASP.NET worker process recycles, the state data is lost.

StateServer: Alternately, StateServer mode uses a stand-alone Microsoft Windows service to store session variables. Because this service is independent of Microsoft Internet Information Server (IIS), it can run on a separate server. You can use this mode for a load-balancing solution because multiple Web servers can share session variables. Although session variables are not lost if you restart IIS, performance is impacted when you cross process boundaries.

SqlServer: If you are greatly concerned about the persistence of session information, you can use SqlServer mode to leverage Microsoft SQL Server to ensure the highest level of reliability. SqlServer mode is similar to out-of-process mode, except that the session data is maintained in a SQL Server. SqlServer mode also enables you to utilize a state store that is located out of the IIS process and that can be located on the local computer or a remote server.

Configuring Session State:
You can configure session state in the configuration section of the Web.config file. The configuration section appears similar to the following:

<configuration>
  <system.web>
   <sessionstate mode="InProc" timeout="20" cookieless="false"
     stateconnectionstring="tcpip=127.0.0.1:42424"
     sqlconnectionstring="data source=127.0.0.1;user id=username;
    password=password">
  </system.web>
</configuration>


Reference: Asp.Net State Management

Changing ASP.net Temporary Files Folder

One of my client was having problems with the small space on the C drive on a server machine which was hosting a ASP.net application. There were few errors in the server error about “No enough space”.Though I would say that in ideal situation it would be best to increase the space on the C: drive as most of the other Operating System related applications also reply on the free space on C: drive, when there is no other easy way of increasing the space on C: drive, administrator can relocate the temporary files folder created by ASP.net.

Please note that ASP.net create a compile version of the site and stores it in its default temporary ASP.net folder. This is usually %Windows Install Folder%\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files (For ASP.Net 2.0). This folder can grow very fast in case web server has large ASP.net sites hosted on that server. Fortunately, ASP.net provides a simple way to change this location. This is stored in the web.config file and can defined in the Global web.config (placed at %Windows Install Folder%Microsoft.NET\Framework\v2.0.50727\CONFIG). To change this path add the new full folder path in the Compilation section of the configuration file. Here is a sample of how this looks like (this must be under System.Web section):

<compilation tempDirectory=“E:\ASP.Net Temporary Folder\” debug=“false“>

One can find the documentation of all different sections of ASP.net configuration file at:

http://msdn2.microsoft.com/en-us/library/b5ysx397(VS.71).aspx

In case when Internet is not available, or you just need a quick reference, there is also a small helpful file in the configuration folder. This file is named “web.config.comments” and is in the CONFIG folder of the ASP.net framework folder.

Microsoft .Net Programming

VB.NET Program Structure C#
Imports System Namespace Hello    Class HelloWorld       Overloads Shared Sub Main(ByVal args() As String)          Dim name As String = "VB.NET"          'See if an argument was passed from the command line           If args.Length = 1 Then name = args(0)           Console.WriteLine("Hello, " & name & "!")       End Sub    End Class End Namespace	using System; namespace Hello {    public class HelloWorld {       public static void Main(string[] args) {          string name = "C#";          // See if an argument was passed from the command line          if (args.Length == 1)             name = args[0];          Console.WriteLine("Hello, " + name + "!");       }    } }
VB.NET Comments C#
' Single line only REM Single line only ''' <summary>XML comments</summary>	// Single line /* Multiple     line  */ /// <summary>XML comments on single line</summary> /** <summary>XML comments on multiple lines</summary> */
VB.NET Data Types C#
Value Types Boolean Byte, SByte Char Short, UShort, Integer, UInteger, Long, ULong Single, Double Decimal Date Reference Types Object String Initializing Dim correct As Boolean = True Dim b As Byte = &H2A   'hex Dim o As Byte = &O52   'octal Dim person As Object = Nothing Dim name As String = "Dwight" Dim grade As Char = "B"c Dim today As Date = #12/31/2007 12:15:00 PM# Dim amount As Decimal = 35.99@ Dim gpa As Single = 2.9! Dim pi As Double = 3.14159265 Dim lTotal As Long = 123456L Dim sTotal As Short = 123S Dim usTotal As UShort = 123US Dim uiTotal As UInteger = 123UI Dim ulTotal As ULong = 123UL Type Information Dim x As Integer Console.WriteLine(x.GetType())          ' Prints System.Int32 Console.WriteLine(GetType(Integer))   ' Prints System.Int32 Console.WriteLine(TypeName(x))        ' Prints Integer Type Conversion Dim d As Single = 3.5 Dim i As Integer = CType(d, Integer)   ' set to 4 (Banker's rounding) i = CInt(d)  ' same result as CType i = Int(d)    ' set to 3 (Int function truncates the decimal)	Value Types bool byte, sbyte char short, ushort, int, uint, long, ulong float, double decimal DateTime   (not a built-in C# type) Reference Types object string Initializing bool correct = true; byte b = 0x2A;   // hex object person = null; string name = "Dwight"; char grade = 'B'; DateTime today = DateTime.Parse("12/31/2007 12:15:00"); decimal amount = 35.99m; float gpa = 2.9f; double pi = 3.14159265; long lTotal = 123456L; short sTotal = 123; ushort usTotal = 123; uint uiTotal = 123; ulong ulTotal = 123; Type Information int x; Console.WriteLine(x.GetType());              // Prints System.Int32 Console.WriteLine(typeof(int));               // Prints System.Int32 Console.WriteLine(x.GetType().Name);   // prints Int32 Type Conversion float d = 3.5f; int i = (int)d;   // set to 3  (truncates decimal)
VB.NET Constants C#
Const MAX_STUDENTS As Integer = 25 ' Can set to a const or var; may be initialized in a constructor ReadOnly MIN_DIAMETER As Single = 4.93	const int MAX_STUDENTS = 25; // Can set to a const or var; may be initialized in a constructor readonly float MIN_DIAMETER = 4.93f;
VB.NET Enumerations C#
Enum Action   Start    [Stop]   ' Stop is a reserved word   Rewind   Forward End Enum Enum Status   Flunk = 50   Pass = 70   Excel = 90 End Enum Dim a As Action = Action.Stop If a <> Action.Start Then _    Console.WriteLine(a.ToString & " is " & a)     ' Prints "Stop is 1" Console.WriteLine(Status.Pass)     ' Prints 70 Console.WriteLine(Status.Pass.ToString())     ' Prints Pass	enum Action {Start, Stop, Rewind, Forward}; enum Status {Flunk = 50, Pass = 70, Excel = 90}; Action a = Action.Stop; if (a != Action.Start)   Console.WriteLine(a + " is " + (int) a);    // Prints "Stop is 1" Console.WriteLine((int) Status.Pass);    // Prints 70 Console.WriteLine(Status.Pass);      // Prints Pass
VB.NET Operators C#
Comparison =  <  >  <=  >=  <> Arithmetic +  -  *  / Mod \  (integer division) ^  (raise to a power) Assignment =  +=  -=  *=  /=  \=  ^=  <<=  >>=  &= Bitwise And   Or   Xor   Not   <<   >> Logical AndAlso   OrElse   And   Or   Xor   Not Note: AndAlso and OrElse perform short-circuit logical evaluations String Concatenation &	Comparison ==  <  >  <=  >=  != Arithmetic +  -  *  / %  (mod) /  (integer division if both operands are ints) Math.Pow(x, y) Assignment =  +=  -=  *=  /=   %=  &=  |=  ^=  <<=  >>=  ++  -- Bitwise &   |   ^   ~   <<   >> Logical &&   ||   &   |   ^   ! Note: && and || perform short-circuit logical evaluations String Concatenation +
VB.NET Choices C#
greeting = IIf(age < 20, "What's up?", "Hello") ' One line doesn't require "End If" If age < 20 Then greeting = "What's up?" If age < 20 Then greeting = "What's up?" Else greeting = "Hello" ' Use : to put two commands on same line If x <> 100 And y < 5 Then x *= 5 : y *= 2   ' Preferred If x <> 100 And y < 5 Then   x *= 5   y *= 2 End If ' To break up any long single line use _ If whenYouHaveAReally < longLine And _   itNeedsToBeBrokenInto2 > Lines Then _   UseTheUnderscore(charToBreakItUp) 'If x > 5 Then   x *= y ElseIf x = 5 Then   x += y ElseIf x < 10 Then   x -= y Else   x /= y End If Select Case color   ' Must be a primitive data type   Case "pink", "red"     r += 1   Case "blue"     b += 1   Case "green"     g += 1   Case Else     other += 1 End Select	greeting = age < 20 ? "What's up?" : "Hello"; if (age < 20)   greeting = "What's up?"; else   greeting = "Hello"; // Multiple statements must be enclosed in {} if (x != 100 && y < 5) {      x *= 5;   y *= 2; }   No need for _ or : since ; is used to terminate each statement. if (x > 5)   x *= y; else if (x == 5)   x += y; else if (x < 10)   x -= y; else   x /= y; // Every case must end with break or goto case switch (color) {                          // Must be integer or string   case "pink":   case "red":    r++;    break;   case "blue":   b++;   break;   case "green": g++;   break;   default:    other++;   break;       // break necessary on default }
VB.NET Loops C#
Pre-test Loops: While c < 10   c += 1 End While Do Until c = 10    c += 1 Loop Do While c < 10   c += 1 Loop For c = 2 To 10 Step 2   Console.WriteLine(c) Next Post-test Loops: Do    c += 1 Loop While c < 10 Do    c += 1 Loop Until c = 10 '  Array or collection looping Dim names As String() = {"Fred", "Sue", "Barney"} For Each s As String In names   Console.WriteLine(s) Next ' Breaking out of loops Dim i As Integer = 0 While (True)   If (i = 5) Then Exit While   i += 1 End While ' Continue to next iteration For i = 0 To 4   If i < 4 Then Continue For   Console.WriteLine(i)   ' Only prints 4 Next	Pre-test Loops:   // no "until" keyword while (c < 10)   c++; for (c = 2; c <= 10; c += 2)   Console.WriteLine(c); Post-test Loop: do   c++; while (c < 10); // Array or collection looping string[] names = {"Fred", "Sue", "Barney"}; foreach (string s in names)   Console.WriteLine(s); // Breaking out of loops int i = 0; while (true) {   if (i == 5)     break;   i++; } // Continue to next iteration for (i = 0; i < 5; i++) {   if (i < 4)     continue;   Console.WriteLine(i);   // Only prints 4 }
VB.NET Arrays C#
Dim nums() As Integer = {1, 2, 3}  For i As Integer = 0 To nums.Length - 1   Console.WriteLine(nums(i)) Next ' 4 is the index of the last element, so it holds 5 elements Dim names(4) As String names(0) = "David" names(5) = "Bobby"  ' Throws System.IndexOutOfRangeException ' Resize the array, keeping the existing values (Preserve is optional) ReDim Preserve names(6) Dim twoD(rows-1, cols-1) As Single twoD(2, 0) = 4.5 Dim jagged()() As Integer = { _   New Integer(4) {}, New Integer(1) {}, New Integer(2) {} } jagged(0)(4) = 5	int[] nums = {1, 2, 3}; for (int i = 0; i < nums.Length; i++)   Console.WriteLine(nums[i]); // 5 is the size of the array string[] names = new string[5]; names[0] = "David"; names[5] = "Bobby";   // Throws System.IndexOutOfRangeException // C# can't dynamically resize an array.  Just copy into new array. string[] names2 = new string[7]; Array.Copy(names, names2, names.Length);   // or names.CopyTo(names2, 0);  float[,] twoD = new float[rows, cols]; twoD[2,0] = 4.5f;  int[][] jagged = new int[3][] {   new int[5], new int[2], new int[3] }; jagged[0][4] = 5;
VB.NET Functions C#
' Pass by value (in, default), reference (in/out), and reference (out)  Sub TestFunc(ByVal x As Integer, ByRef y As Integer, ByRef z As Integer)   x += 1   y += 1   z = 5 End Sub Dim a = 1, b = 1, c As Integer   ' c set to zero by default  TestFunc(a, b, c) Console.WriteLine("{0} {1} {2}", a, b, c)   ' 1 2 5 ' Accept variable number of arguments Function Sum(ByVal ParamArray nums As Integer()) As Integer   Sum = 0    For Each i As Integer In nums     Sum += i   Next End Function   ' Or use Return statement like C# Dim total As Integer = Sum(4, 3, 2, 1)   ' returns 10 ' Optional parameters must be listed last and must have a default value Sub SayHello(ByVal name As String, Optional ByVal prefix As String = "")   Console.WriteLine("Greetings, " & prefix & " " & name) End Sub SayHello("Strangelove", "Dr.") SayHello("Madonna")	// Pass by value (in, default), reference (in/out), and reference (out) void TestFunc(int x, ref int y, out int z) {   x++;     y++;   z = 5; } int a = 1, b = 1, c;  // c doesn't need initializing TestFunc(a, ref b, out c); Console.WriteLine("{0} {1} {2}", a, b, c);  // 1 2 5 // Accept variable number of arguments int Sum(params int[] nums) {   int sum = 0;   foreach (int i in nums)     sum += i;   return sum; } int total = Sum(4, 3, 2, 1);   // returns 10 /* C# doesn't support optional arguments/parameters.  Just create two different versions of the same function. */  void SayHello(string name, string prefix) {   Console.WriteLine("Greetings, " + prefix + " " + name); }  void SayHello(string name) {   SayHello(name, ""); }
VB.NET Strings C#
Special character constants (all also accessible from ControlChars class) vbCrLf, vbCr, vbLf, vbNewLine vbNullString vbTab vbBack vbFormFeed vbVerticalTab "" ' String concatenation (use & or +) Dim school As String = "Harding" & vbTab school = school & "University" ' school is "Harding (tab) University" ' Chars Dim letter As Char = school.Chars(0)   ' letter is H letter = Convert.ToChar(65)                ' letter is A letter = Chr(65)                                 ' same thing Dim word() As Char = school.ToCharArray() ' word holds Harding ' No string literal operator Dim msg As String = "File is c:\temp\x.dat" ' String comparison Dim mascot As String = "Bisons" If (mascot = "Bisons") Then   ' true If (mascot.Equals("Bisons")) Then   ' true If (mascot.ToUpper().Equals("BISONS")) Then  ' true If (mascot.CompareTo("Bisons") = 0) Then   ' true ' String matching with Like - Regex is more powerful If ("John 3:16" Like "Jo[Hh]? #:*") Then   'true ' Substring s = mascot.Substring(2, 3)) ' s is "son" ' Replacement s = mascot.Replace("sons", "nomial")) ' s is "Binomial" ' Split Dim names As String = "Frank,Becky,Ethan,Braden" Dim parts() As String = names.Split(",".ToCharArray())   ' One name in each slot ' Date to string Dim dt As New DateTime(1973, 10, 12) Dim s As String = "My birthday: " & dt.ToString("MMM dd, yyyy")   ' Oct 12, 1973 ' Integer to String Dim x As Integer = 2 Dim y As String = x.ToString()     ' y is "2" ' String to Integer Dim x As Integer = Convert.ToInt32("-5")     ' x is -5 ' Mutable string Dim buffer As New System.Text.StringBuilder("two ") buffer.Append("three ") buffer.Insert(0, "one ") buffer.Replace("two", "TWO") Console.WriteLine(buffer)         ' Prints "one TWO three"	Escape sequences \r    // carriage-return \n    // line-feed \t    // tab \\    // backslash \"    // quote // String concatenation string school = "Harding\t"; school = school + "University";   // school is "Harding (tab) University" // Chars char letter = school[0];            // letter is H letter = Convert.ToChar(65);     // letter is A letter = (char)65;                    // same thing char[] word = school.ToCharArray();   // word holds Harding // String literal string msg = @"File is c:\temp\x.dat"; // same as string msg = "File is c:\\temp\\x.dat"; // String comparison string mascot = "Bisons"; if (mascot == "Bisons")    // true if (mascot.Equals("Bisons"))   // true if (mascot.ToUpper().Equals("BISONS"))   // true if (mascot.CompareTo("Bisons") == 0)    // true // String matching - No Like equivalent, use Regex // Substring s = mascot.Substring(2, 3))     // s is "son" // Replacement s = mascot.Replace("sons", "nomial"))     // s is "Binomial" // Split string names = "Frank,Becky,Ethan,Braden"; string[] parts = names.Split(",".ToCharArray());   // One name in each slot // Date to string DateTime dt = new DateTime(1973, 10, 12); string s = dt.ToString("MMM dd, yyyy");     // Oct 12, 1973 // int to string int x = 2; string y = x.ToString();     // y is "2" // string to int int x = Convert.ToInt32("-5");     // x is -5 // Mutable string System.Text.StringBuilder buffer = new System.Text.StringBuilder("two "); buffer.Append("three "); buffer.Insert(0, "one "); buffer.Replace("two", "TWO"); Console.WriteLine(buffer);     // Prints "one TWO three"
VB.NET Regular Expressions C#
Imports System.Text.RegularExpressions ' Match a string pattern Dim r As New Regex("j[aeiou]h?. \d:*", RegexOptions.IgnoreCase Or _         RegexOptions.Compiled) If (r.Match("John 3:16").Success) Then   'true     Console.WriteLine("Match") End If ' Find and remember all matching patterns Dim s As String = "My number is 305-1881, not 305-1818." Dim r As New Regex("(\d+-\d+)") Dim m As Match = r.Match(s)     ' Matches 305-1881 and 305-1818 While m.Success     Console.WriteLine("Found number: " & m.Groups(1).Value & " at position " _             & m.Groups(1).Index.ToString)     m = m.NextMatch() End While ' Remeber multiple parts of matched pattern Dim r As New Regex("(\d\d):(\d\d) (am|pm)") Dim m As Match = r.Match("We left at 03:15 pm.") If m.Success Then     Console.WriteLine("Hour: " & m.Groups(1).ToString)       ' 03     Console.WriteLine("Min: " & m.Groups(2).ToString)         ' 15     Console.WriteLine("Ending: " & m.Groups(3).ToString)   ' pm End If ' Replace all occurrances of a pattern Dim r As New Regex("h\w+?d", RegexOptions.IgnoreCase) Dim s As String = r.Replace("I heard this was HARD!", "easy")   ' I easy this was easy! ' Replace matched patterns Dim s As String = Regex.Replace("123 < 456", "(\d+) . (\d+)", "$2 > $1")   ' 456 > 123 ' Split a string based on a pattern Dim names As String = "Frank, Becky, Ethan, Braden" Dim r As New Regex(",\s*") Dim parts() As String = r.Split(names)   ' One name in each slot	using System.Text.RegularExpressions; // Match a string pattern Regex r = new Regex(@"j[aeiou]h?. \d:*", RegexOptions.IgnoreCase |         RegexOptions.Compiled); if (r.Match("John 3:16").Success)   // true     Console.WriteLine("Match"); // Find and remember all matching patterns string s = "My number is 305-1881, not 305-1818."; Regex r = new Regex("(\\d+-\\d+)"); // Matches 305-1881 and 305-1818 for (Match m = r.Match(s); m.Success; m = m.NextMatch())     Console.WriteLine("Found number: " + m.Groups[1] + " at position " +         m.Groups[1].Index); // Remeber multiple parts of matched pattern Regex r = new Regex("@(\d\d):(\d\d) (am|pm)"); Match m = r.Match("We left at 03:15 pm."); if (m.Success) {     Console.WriteLine("Hour: " + m.Groups[1]);       // 03     Console.WriteLine("Min: " + m.Groups[2]);         // 15     Console.WriteLine("Ending: " + m.Groups[3]);   // pm } // Replace all occurrances of a pattern Regex r = new Regex("h\\w+?d", RegexOptions.IgnoreCase); string s = r.Replace("I heard this was HARD!", "easy"));   // I easy this was easy! // Replace matched patterns string s = Regex.Replace("123 < 456", @"(\d+) . (\d+)", "$2 > $1");   // 456 > 123 // Split a string based on a pattern string names = "Frank, Becky, Ethan, Braden"; Regex r = new Regex(@",\s*"); string[] parts = r.Split(names);   // One name in each slot
VB.NET Exception Handling C#
' Throw an exception Dim ex As New Exception("Something is really wrong.") Throw  ex  ' Catch an exception Try    y = 0   x = 10 / y Catch ex As Exception When y = 0 ' Argument and When is optional   Console.WriteLine(ex.Message) Finally   Beep() End Try ' Deprecated unstructured error handling On Error GoTo MyErrorHandler ... MyErrorHandler: Console.WriteLine(Err.Description)	// Throw an exception Exception up = new Exception("Something is really wrong."); throw up;  // ha ha // Catch an exception try {    y = 0;   x = 10 / y; } catch (Exception ex) {   // Argument is optional, no "When" keyword    Console.WriteLine(ex.Message); } finally {   Microsoft.VisualBasic.Interaction.Beep(); }
VB.NET Namespaces C#
Namespace Harding.Compsci.Graphics    ... End Namespace ' or Namespace Harding   Namespace Compsci     Namespace Graphics        ...     End Namespace   End Namespace End Namespace Imports Harding.Compsci.Graphics	namespace Harding.Compsci.Graphics {   ... } // or namespace Harding {   namespace Compsci {     namespace Graphics {       ...     }   } } using Harding.Compsci.Graphics;
VB.NET Classes / Interfaces C#
Accessibility keywords Public Private Friend                    Protected Protected Friend Shared ' Inheritance Class FootballGame   Inherits Competition   ... End Class  ' Interface definition Interface IAlarmClock    ... End Interface // Extending an interface  Interface IAlarmClock   Inherits IClock   ... End Interface // Interface implementation Class WristWatch    Implements IAlarmClock, ITimer     ... End Class	Accessibility keywords public private internal protected protected internal static // Inheritance class FootballGame : Competition {   ... } // Interface definition interface IAlarmClock {   ... } // Extending an interface  interface IAlarmClock : IClock {   ... } // Interface implementation class WristWatch : IAlarmClock, ITimer {    ... }
VB.NET Constructors / Destructors C#
Class SuperHero   Private _powerLevel As Integer   Public Sub New()     _powerLevel = 0   End Sub   Public Sub New(ByVal powerLevel As Integer)     Me._powerLevel = powerLevel   End Sub   Protected Overrides Sub Finalize()     ' Desctructor code to free unmanaged resources     MyBase.Finalize()   End Sub End Class	class SuperHero {   private int _powerLevel;   public SuperHero() {      _powerLevel = 0;   }   public SuperHero(int powerLevel) {     this._powerLevel= powerLevel;    }   ~SuperHero() {     // Destructor code to free unmanaged resources.     // Implicitly creates a Finalize method   } }
VB.NET Using Objects C#
Dim hero As SuperHero = New SuperHero ' or Dim hero As New SuperHero With hero   .Name = "SpamMan"   .PowerLevel = 3 End With hero.Defend("Laura Jones") hero.Rest()     ' Calling Shared method ' or SuperHero.Rest() Dim hero2 As SuperHero = hero  ' Both reference the same object hero2.Name = "WormWoman" Console.WriteLine(hero.Name)   ' Prints WormWoman hero = Nothing    ' Free the object If hero Is Nothing Then _   hero = New SuperHero Dim obj As Object = New SuperHero If TypeOf obj Is SuperHero Then _   Console.WriteLine("Is a SuperHero object.") ' Mark object for quick disposal Using reader As StreamReader = File.OpenText("test.txt")   Dim line As String = reader.ReadLine()   While Not line Is Nothing     Console.WriteLine(line)     line = reader.ReadLine()   End While End Using	SuperHero hero = new SuperHero(); // No "With" construct hero.Name = "SpamMan"; hero.PowerLevel = 3; hero.Defend("Laura Jones"); SuperHero.Rest();   // Calling static method SuperHero hero2 = hero;   // Both reference the same object hero2.Name = "WormWoman"; Console.WriteLine(hero.Name);   // Prints WormWoman hero = null ;   // Free the object if (hero == null)   hero = new SuperHero(); Object obj = new SuperHero();  if (obj is SuperHero)   Console.WriteLine("Is a SuperHero object."); // Mark object for quick disposal using (StreamReader reader = File.OpenText("test.txt")) {   string line;   while ((line = reader.ReadLine()) != null)     Console.WriteLine(line); }
VB.NET Structs C#
Structure StudentRecord   Public name As String   Public gpa As Single   Public Sub New(ByVal name As String, ByVal gpa As Single)     Me.name = name     Me.gpa = gpa   End Sub End Structure Dim stu As StudentRecord = New StudentRecord("Bob", 3.5) Dim stu2 As StudentRecord = stu   stu2.name = "Sue" Console.WriteLine(stu.name)    ' Prints Bob Console.WriteLine(stu2.name)  ' Prints Sue	struct StudentRecord {   public string name;   public float gpa;   public StudentRecord(string name, float gpa) {     this.name = name;     this.gpa = gpa;   } } StudentRecord stu = new StudentRecord("Bob", 3.5f); StudentRecord stu2 = stu;   stu2.name = "Sue"; Console.WriteLine(stu.name);    // Prints Bob Console.WriteLine(stu2.name);   // Prints Sue
VB.NET Properties C#
Private _size As Integer Public Property Size() As Integer   Get     Return _size   End Get   Set (ByVal Value As Integer)     If Value < 0 Then       _size = 0     Else       _size = Value     End If   End Set End Property foo.Size += 1	private int _size; public int Size {   get {     return _size;   }   set {     if (value < 0)       _size = 0;     else       _size = value;   } } foo.Size++;
VB.NET Delegates / Events C#
Delegate Sub MsgArrivedEventHandler(ByVal message As String) Event MsgArrivedEvent As MsgArrivedEventHandler ' or to define an event which declares a delegate implicitly Event MsgArrivedEvent(ByVal message As String) AddHandler MsgArrivedEvent, AddressOf My_MsgArrivedCallback ' Won't throw an exception if obj is Nothing RaiseEvent MsgArrivedEvent("Test message") RemoveHandler MsgArrivedEvent, AddressOf My_MsgArrivedCallback Imports System.Windows.Forms Dim WithEvents MyButton As Button   ' WithEvents can't be used on local variable MyButton = New Button Private Sub MyButton_Click(ByVal sender As System.Object, _   ByVal e As System.EventArgs) Handles MyButton.Click   MessageBox.Show(Me, "Button was clicked", "Info", _     MessageBoxButtons.OK, MessageBoxIcon.Information) End Sub	delegate void MsgArrivedEventHandler(string message); event MsgArrivedEventHandler MsgArrivedEvent; // Delegates must be used with events in C# MsgArrivedEvent += new MsgArrivedEventHandler(My_MsgArrivedEventCallback); MsgArrivedEvent("Test message");    // Throws exception if obj is null MsgArrivedEvent -= new MsgArrivedEventHandler(My_MsgArrivedEventCallback); using System.Windows.Forms; Button MyButton = new Button();  MyButton.Click += new System.EventHandler(MyButton_Click); private void MyButton_Click(object sender, System.EventArgs e) {   MessageBox.Show(this, "Button was clicked", "Info",     MessageBoxButtons.OK, MessageBoxIcon.Information); }
VB.NET Console I/O C#
Console.Write("What's your name? ") Dim name As String = Console.ReadLine() Console.Write("How old are you? ") Dim age As Integer = Val(Console.ReadLine()) Console.WriteLine("{0} is {1} years old.", name, age)  ' or Console.WriteLine(name & " is " & age & " years old.") Dim c As Integer c = Console.Read()    ' Read single char Console.WriteLine(c)   ' Prints 65 if user enters "A"	Console.Write("What's your name? "); string name = Console.ReadLine(); Console.Write("How old are you? "); int age = Convert.ToInt32(Console.ReadLine()); Console.WriteLine("{0} is {1} years old.", name, age); // or Console.WriteLine(name + " is " + age + " years old."); int c = Console.Read();  // Read single char Console.WriteLine(c);    // Prints 65 if user enters "A"
VB.NET File I/O C#
Imports System.IO ' Write out to text file Dim writer As StreamWriter = File.CreateText("c:\myfile.txt") writer.WriteLine("Out to file.") writer.Close() ' Read all lines from text file Dim reader As StreamReader = File.OpenText("c:\myfile.txt") Dim line As String = reader.ReadLine() While Not line Is Nothing   Console.WriteLine(line)   line = reader.ReadLine() End While reader.Close() ' Write out to binary file Dim str As String = "Text data" Dim num As Integer = 123 Dim binWriter As New BinaryWriter(File.OpenWrite("c:\myfile.dat"))  binWriter.Write(str)  binWriter.Write(num)  binWriter.Close() ' Read from binary file Dim binReader As New BinaryReader(File.OpenRead("c:\myfile.dat")) str = binReader.ReadString() num = binReader.ReadInt32() binReader.Close()	using System.IO; // Write out to text file StreamWriter writer = File.CreateText("c:\\myfile.txt"); writer.WriteLine("Out to file."); writer.Close(); // Read all lines from text file StreamReader reader = File.OpenText("c:\\myfile.txt"); string line = reader.ReadLine(); while (line != null) {   Console.WriteLine(line);   line = reader.ReadLine(); } reader.Close(); // Write out to binary file string str = "Text data"; int num = 123; BinaryWriter binWriter = new BinaryWriter(File.OpenWrite("c:\\myfile.dat")); binWriter.Write(str); binWriter.Write(num); binWriter.Close(); // Read from binary file BinaryReader binReader = new BinaryReader(File.OpenRead("c:\\myfile.dat")); str = binReader.ReadString(); num = binReader.ReadInt32(); binReader.Close();