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Abstract Methods

VB.NET	C#
Public MustInherit Class AbstractClass Protected MustOverride Sub AbstractMethod() End Class	public abstract class AbstractClass { protected abstract void AbstractMethod(); }

Access Modifiers

VB.NET	C#
Public Private Friend Protected Protected Friend	public private internal protected protected internal

Arrays

Unsized Array

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VB.NET	C#
Dim myArray() As Integer	int[] myArray = null;

Sized Array

VB.NET	C#
Dim myArray(1) As Integer	int[] myArray = new int[2];

Access Array Element

VB.NET	C#
x = myArray(0)	x = myArray[0];

Jagged Array

VB.NET	C#
Dim myArray(1)() As Integer	int[][] myArray = new int[2][];

Rectangular Array

VB.NET	C#
Dim myArray(1, 2) As Integer	int[,] myArray = new int[2, 3];

Resizing Array

VB.NET	C#
ReDim Preserve myArray(newSize) ReDim myArray(newSize)	System.Array.Resize(ref myArray, newSize + 1); myArray = new foo[newSize + 1];

Initializing Array

VB.NET	C#
myArray = New Integer(1) {1,2}	myArray = new int[2] {1, 2};

Empty Array

VB.NET	C#
Dim myArray As String() = New String() {}	string[] myArray = new string[0];

Attributes

Class Attribute

VB.NET	C#
<Serializable()> Public Class Foo	[Serializable()] public class Foo

Method Attribute

VB.NET	C#
<DebuggerHidden()> Public Sub Method()	[System.Diagnostics.DebuggerHidden()] public void Method()

Method Return Type Attribute

VB.NET	C#
Public Function Method() As <ReturnAttribute> Integer	[return: ReturnAttribute] public int TestReturnValueAttribute()

Method Parameter Attribute

VB.NET	C#
Public Sub Method(<ParamAttribute> ByVal x As Integer)	public void Method([ParamAttribute] int x)

Named Properties in Attributes

Attributes have a special syntax which allows setting properties of the attribute type after the attribute constructor arguments - called named properties. These have the same syntax as named arguments in VB, but not in C#. Note that in the following example, 'property1' and 'property2' are named properties, not named arguments - the attribute type constructor for this example would only have one parameter, not three. Named arguments are not available for attributes.

VB.NET	C#
'note: property1 and property2 are named properties: <FooAttribute(arg, property1:=1, property2:=2)> Public Class Foo End Class	//note: property1 and property2 are named properties: [FooAttribute(arg, property1=1, property2=2)] public class Foo { }

AutoEventWireup

AutoEventWireup is an ASP.NET page attribute that will allow automatic wireup of page events when this attribute is set to true on the page. The AutoEventWireup page attribute leads to the following options for the associated VB and C# code-behind class:

AutoEventWireup = true

This allows specifying Page_Load, Page_Init, etc. event handler methods by name alone. In VB, no Handles clause is appended and in C# no event wireup code is required. Provided the method name matches, the methods will automatically handle the associated events. If you do erroneously code any event wireup code, this will cause the event handler to execute twice.

AutoEventWireup = false

This requires that you code the event handler wireup. In VB, you would specify a Handles clause and in C# you would include code to subscribe to the events. However, in C# the problem is that the first page event occurs before the event wireup code has a chance to execute. A common C# approach in this case is to override the base class OnLoad, OnInit, etc. methods, dispensing with the need to have event handler wireup code for the page events. For these cases (Handles used instead of setting AutoEventWireup to true), Instant C# automatically adds event wireups corresponding to all 'Page' methods where a Handles clause is used to the Page_Init or OnInit method if it exists. If no Page_Init or OnInit method exists, a new OnInit method is added. The event wireup for the Page_Init method is added to the class constructor - if no constructor exists, then a constructor is added by Instant C#.

'ByRef' (VB) and 'ref' (C#) Parameters

VB.NET	C#
Sub Method1(ByRef myParam As Integer) End Sub Sub Method2 Method1(foo) End Sub	void Method1(ref int myParam) { } void Method2() { Method2(ref foo); //'ref' is required in the method call also }

Casting

The closest equivalent to the standard VB casting operators (CType and the corresponding CInt, CStr, etc.) are calls to the System.Convert methods if the appropriate method exists, otherwise they are converted to the standard C# casting operator.
The behavior of both the System.Convert methods and the standard C# casting operator are subtly different from the VB casting operators though, so you should always test the behavior of your converted code.
The C# equivalent to VB's 'DirectCast' is the standard C# casting operator.
The VB 'TryCast' operator always converts to the C# 'as' operator. The C# 'as' operator converts to the VB 'TryCast' operator, except for the case of nullable types, in which case you must use the 'CType' operator.

VB.NET	C#
x = CBool(y) x = CInt(y) x = CDec(y) x = CChar(y) x = CStr(y) x = CDate(y) x = CObj(y) x = CType(y, Foo) x = DirectCast(y, Foo) x = TryCast(y, Foo)	using System; x = Convert.ToBoolean(y); x = Convert.ToInt32(y); x = Convert.ToDecimal(y); x = Convert.ToChar(y); x = Convert.ToString(y); x = Convert.ToDateTime(y); x = (object)y; x = (Foo)y; x = (Foo)y; x = y as Foo;

A further complication is that C# integer casts always truncate, while the VB integer conversion operators always round. For this reason, in order to achieve the same results as the C# casts, a call to the .NET Math.Truncate function is required prior to the call to the CInt, CLng, and CShort operators when converting C# integer casts.

C#	VB.NET
i = (int)someDouble;	i = CInt(Math.Truncate(someDouble))

Collection Initializers

In VB, the keyword 'From' is used to initialize collections during construction.

VB.NET	C#
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