Complete Comparison for VB.NET and C#

VB.NET

C#

• Support for optional parameters - very handy for some COM interoperability.
• Support for late binding with Option Strict off - type safety at compile time goes out of the window, but legacy libraries which don't have strongly typed interfaces become easier to use.
• Support for named indexers.
• Various legacy VB functions (provided in the Microsoft.VisualBasic namespace, and can be used by other languages with a reference to the Microsoft.VisualBasic.dll). Many of these can be harmful to performance if used unwisely, however, and many people believe they should be avoided for the most part.
• The with construct: it's a matter of debate as to whether this is an advantage or not, but it's certainly a difference.
• Simpler (in expression - perhaps more complicated in understanding) event handling, where a method can declare that it handles an event, rather than the handler having to be set up in code.
• The ability to implement interfaces with methods of different names. (Arguably this makes it harder to find the implementation of an interface, however.)
• Catch ... When ... clauses, which allow exceptions to be filtered based on runtime expressions rather than just by type.
• The VB.NET parts of Visual Studio .NET compiles your code in the background. While this is considered as an advantage for small projects, people creating very large projects have found that the IDE slows down considerably as the project gets larger.

• XML documentation generated from source code comments. (This is coming in VB.NET with Whidbey (the code name for the next version of Visual Studio and .NET), and there are tools which will do it with existing VB.NET code already.)
• Operator overloading - again, coming to VB.NET in Whidbey.
• Language support for unsigned types (you can use them from VB.NET, but they aren't in the language itself). Again, support for these is coming to VB.NET in Whidbey.
• The using statement, which makes unmanaged resource disposal simple.
• Explicit interface implementation, where an interface which is already implemented in a base class can be re-implemented separately in a derived class. Arguably this makes the class harder to understand, in the same way that member hiding normally does.
• Unsafe code. This allows pointer arithmetic etc, and can improve performance in some situations. However, it is not to be used lightly, as a lot of the normal safety of C# is lost (as the name implies). Note that unsafe code is still managed code, i.e., it is compiled to IL, JITted, and run within the CLR.

Purpose

VB.NET

C#

Declare a variable

Private, Public, Friend, Protected, Static1, Shared, Dim

declarators (keywords include user-defined types and built-in types)

Declare a named constant

Const

const

Create a new object

New, CreateObject()

new

Function/method does not return a value

Sub

void

Overload a function or method (Visual Basic: overload a procedure or method)

Overloads

(No language keyword required for this purpose)

Refer to the current object

Me

this

Make a nonvirtual call to a virtual method of the current object

MyClass

n/a

Retrieve character from a string

GetChar Function

[]

Declare a compound data type (Visual Basic: Structure)

Structure <members> End Structure

struct, class, interface

Initialize an object (constructors)

Sub New()

Constructors, or system default type constructors

Terminate an object directly

n/a

n/a

Method called by the system just before garbage collection reclaims an object7

Finalize

destructor

Initialize a variable where it is declared

Dim x As Long = 5

Dim c As New _
   Car(FuelTypeEnum.Gas)

// initialize to a value:
int x = 123;
// or use default 
// constructor:
int x = new int();

Take the address of a function

AddressOf (For class members, this operator returns a reference to a function in the form of a delegate instance)

delegate

Declare that an object can be modified asynchronously

n/a

volatile

Force explicit declaration of variables

Option Explicit

n/a. (All variables must be declared prior to use)

Test for an object variable that does not refer to an object

obj = Nothing

obj == null

Value of an object variable that does not refer to an object

Nothing

null

Test for a database null expression

IsDbNull

n/a

Test whether a Variant variable has been initialized

n/a

n/a

Define a default property

Default

by using indexers

Refer to a base class

MyBase

base

Declare an interface

Interface

interface

Specify an interface to be implemented

Implements (statement)

class C1 : I1

Declare a class

Class <implementation>

class

Specify that a class can only be inherited. An instance of the class cannot be created.

MustInherit

abstract

Specify that a class cannot be inherited

NotInheritable

sealed

Declare an enumerated type

Enum <members> End Enum

enum

Declare a class constant

Const

const (Applied to a field declaration)

Derive a class from a base class

Inherits C2

class C1 : C2

Override a method

Overrides

override

Declare a method that must be implemented in a deriving class

MustOverride

abstract

Declare a method that can't be overridden

NotOverridable (Methods are not overridable by default.)

sealed

Declare a virtual method, property (Visual Basic), or property accessor (C#, C++)

Overridable

virtual

Hide a base class member in a derived class

Shadowing

n/a

Declare a typesafe reference to a class method

Delegate

delegate

Specify that a variable can contain an object whose events you wish to handle

WithEvents

(Write code - no specific keyword)

Specify the events for which an event procedure will be called

Handles (Event procedures can still be associated with a WithEvents variable by naming pattern.)

n/a

Evaluate an object expression once, in order to access multiple members

With objExpr 
  <.member>
  <.member> 
End With

n/a

Structured exception handling

Try <attempt>
Catch
<handle errors>
Finally
<always execute>
End Try

try, catch, finally, throw

Decision structure (selection)

Select Case ..., Case, Case Else, End Select

switch, case, default, goto, break

Decision structure (if ... then)

If ... Then, ElseIf ... Then, Else, End If

if, else

Loop structure (conditional)

While, Do [While, Until] ..., Loop [While, Until]

do, while, continue

Loop structure (iteration)

For ..., [Exit For], Next<BR>For Each ..., [Exit For,] Next

for, foreach

Declare an array

Dim a() As Long

int[] x = new int[5];

Initialize an array

Dim a() As Long = {3, 4, 5}

int[] x = new int[5] {
        1, 2, 3, 4, 5};

Reallocate array

Redim

n/a

Visible outside the project or assembly

Public

public

Invisible outside the assembly (C#/Visual Basic) or within the package (Visual J#, JScript)

Friend

internal

Visible only within the project (for nested classes, within the enclosing class)

Private

private

Accessible outside class and project or module

Public

public

Accessible outside the class, but within the project

Friend

internal

Only accessible within class or module

Private

private

Only accessible to current and derived classes

Protected

protected

Preserve procedure's local variables

Static

n/a

Shared by all instances of a class

Shared

static

Comment code

'
Rem

//, /* */ for multi-line comments
/// for XML comments

Case-sensitive?

No

Yes

Call Windows API

Declare <API>

use Platform Invoke

Declare and raise an event

Event, RaiseEvent

event

Threading primitives

SyncLock

lock

Go to

Goto

goto

Purpose/Size

VB.NET

C#

Decimal

Decimal

decimal

Date

Date

DateTime

(varies)

String

string

1 byte

Byte

byte

2 bytes

Boolean

bool

2 bytes

Short, Char (Unicode character)

short, char (Unicode character)

4 bytes

Integer

int

8 bytes

Long

long

4 bytes

Single

float

8 bytes

Double

double

Purpose

VB.NET

C#

Integer division

\

/

Modulus (division returning only the remainder)

Mod

%

Exponentiation

^

n/a

Integer division Assignment

\=

/=

Concatenate

&= NEW

+=

Modulus

n/a

%=

Bitwise-AND

n/a

&=

Bitwise-exclusive-OR

n/a

^=

Bitwise-inclusive-OR

n/a

|=

Equal

=

==

Not equal

<>

!=

Compare two object reference variables

Is

==

Compare object reference type

TypeOf x Is Class1

x is Class1

Concatenate strings

&

+

Shortcircuited Boolean AND

AndAlso

&&

Shortcircuited Boolean OR

OrElse

||

Scope resolution

.

. and base

Array element

()

[ ]

Type cast

Cint, CDbl, ..., CType

(type)

Postfix increment

n/a

++

Postfix decrement

n/a

--

Indirection

n/a

* (unsafe mode only)

Address of

AddressOf

& (unsafe mode only; also see fixed)

Logical-NOT

Not

!

One's complement

Not

~

Prefix increment

n/a

++

Prefix decrement

n/a

--

Size of type

n/a

sizeof

Bitwise-AND

And

&

Bitwise-exclusive-OR

Xor

^

Bitwise-inclusive-OR

Or

|

Logical-AND

And

&&

Logical-OR

Or

||

Conditional

If Function ()

?:

Pointer to member

n/a

. (Unsafe mode only)

Purpose

VB.NET

C#

Declaring Variables

Dim x As Integer
Public x As Integer = 10

int x;
int x = 10;

Comments

' comment
x = 1  ' comment
Rem comment

// comment
/* multiline
 comment */

Assignment Statements

nVal = 7

nVal = 7;

Conditional Statements

If nCnt <= nMax Then
   ' Same as nTotal = 
   ' nTotal + nCnt.
   nTotal += nCnt  
   ' Same as nCnt = nCnt + 1.
   nCnt += 1       
Else
   nTotal += nCnt
   nCnt -= 1       
End If

if (nCnt <= nMax)
{
   nTotal += nCnt;
   nCnt++;
}
else
{
   nTotal +=nCnt;
   nCnt--;
}

Selection Statements

Select Case n
   Case 0
      MsgBox ("Zero")  
     ' Visual Basic .NET exits
     ' the Select at 
     ' the end of a Case.
   Case 1
      MsgBox ("One")
   Case 2 
      MsgBox ("Two")
   Case Else
      MsgBox ("Default")
End Select

switch(n) 
{
   case 0:
      Console.WriteLine("Zero");
      break;
   case 1:
      Console.WriteLine("One");
      break;
   case 2:
      Console.WriteLine("Two");
      break;
   default:
      Console.WriteLine("?");
      break;
}

FOR Loops

For n = 1 To 10 
   MsgBox("The number is " & n)
Next

For Each prop In obj
    prop = 42
Next prop

for (int i = 1; i <= 10; i++) 
   Console.WriteLine(
      "The number is {0}", i);
foreach(prop current in obj)
{
   current=42;
}

Hiding Base Class Members

Public Class BaseCls
   ' The element to be shadowed
   Public Z As Integer = 100   
   public Sub Test()
      System.Console.WriteLine( _
        "Test in BaseCls")
   End Sub
End Class

Public Class DervCls
   Inherits BaseCls
   ' The shadowing element.
   Public Shadows Z As String = "*"
   public Shadows Sub Test()
      System.Console.WriteLine( _
          "Test in DervCls")
   End Sub
End Class

Public Class UseClasses
  ' DervCls widens to BaseCls. 
  Dim BObj As BaseCls = 
          New DervCls()
  ' Access through derived 
  ' class.
  Dim DObj As DervCls = 
       New DervCls()

  Public Sub ShowZ()
    System.Console.WriteLine( _
     "Accessed through base "&_
     "class: "  & BObj.Z)
    System.Console.WriteLine(_
    "Accessed through derived "&_
    "class: " & DObj.Z)
    BObj.Test()
    DObj.Test()
  End Sub 
End Class

public class BaseCls
{
   // The element to be hidden
   public int Z = 100;   
   public void Test()
   {
      System.Console.WriteLine(
        "Test in BaseCls");
   }
}

public class DervCls : BaseCls
{
  // The hiding element
  public new string Z = "*";   
  public new void Test()
  {
    System.Console.WriteLine(
      "Test in DervCls");
  }
}

public class UseClasses
{
  // DervCls widens to BaseCls
  BaseCls BObj = new DervCls();  
   // Access through derived 
   //class 
  DervCls DObj = new DervCls();  
  public void ShowZ()
  {
    System.Console.WriteLine(
    "Accessed through " +
      "base class: {0}", 
      BObj.Z);
    System.Console.WriteLine(
    "Accessed through" +
      " derived class:{0}",
      DObj.Z);
    BObj.Test();
    DObj.Test();
   }
}

WHILE Loops

' Test at start of loop
While n < 100 .
   ' Same as n = n + 1.
   n += 1     
End While '

while (n < 100)
   n++;

Parameter Passing by Value

' The argument Y is 
'passed by value.
Public Sub ABC( _
  ByVal y As Long) 
'If ABC changes y, the
' changes do not affect x.
End Sub
   
ABC(x) ' Call the procedure.
' You can force parameters to 
' be passed by value, 
' regardless of how 
' they are declared, 
' by enclosing 
' the parameters in 
' extra parentheses.
ABC((x))

/* Note that there is 
no way to pass reference 
types (objects) strictly 
by value. You can choose 
to either pass the reference 
(essentially a pointer), or 
a reference to the reference 
(a pointer to a pointer).*/
// The method:
void ABC(int x)
{
   ...
}
// Calling the method:
ABC(i);

Parameter Passing by Reference

Public Sub ABC(ByRef y As Long) 
' The parameter y is declared 
'by referece:
' If ABC changes y, the changes are
' made to the value of x.
End Sub

ABC(x) ' Call the procedure.

/* Note that there is no
 way to pass reference types 
 (objects)  strictly by value.
 You can choose to  either 
 pass the reference 
 (essentially  a pointer), 
 or a reference to the 
 reference (a pointer to a 
 pointer).*/
// Note also that unsafe C# 
//methods can take pointers 
//just like C++ methods. For 
//details, see unsafe.
// The method:
void ABC(ref int x)
{
   ...
}
// Calling the method:
ABC(ref i);

Structured Exception Handling

Try
   If x = 0 Then
      Throw New Exception( _
         "x equals zero")
   Else
      Throw New Exception( _
        "x does not equal zero")
   End If
Catch err As System.Exception
   MsgBox( _
   "Error: " & Err.Description)
Finally
   MsgBox( _
   "Executing finally block.")
End Try

// try-catch-finally
try
{
  if (x == 0)
   throw new System.Exception(
     "x equals zero");
  else
   throw new System.Exception(
     "x does not equal zero");
}
catch (System.Exception err)
{
  System.Console.WriteLine(
              err.Message);
}
finally
{
  System.Console.WriteLine(
   "executing finally block");
}

Set an Object Reference to Nothing

o = Nothing

o = null;

Initializing Value Types

Dim dt as New System.DateTime( _
  2001, 4, 12, 22, 16, 49, 844)

System.DateTime dt = 
 new System.DateTime(
 2001, 4, 12, 22, 16, 
      49, 844);

VB.NET

C#

Visual Basic 2005 has many new and improved language features -- such as inheritance, interfaces, overriding, shared members, and overloading -- that make it a powerful object-oriented programming language. As a Visual Basic developer, you can now create multithreaded, scalable applications using explicit multithreading. This language has following new features,

1. Continue Statement, which immediately skips to the next iteration of a Do, For, or While loop.
2. IsNot operator, which you can avoid using the Not and Is operators in an awkward order.
3. 3. Using...End. Using statement block ensures disposal of a system resource when your code leaves the block for any reason.

   Public Sub setbigbold( _
       ByVal c As Control)
   Using nf As New _
     System.Drawing.Font("Arial",_
     12.0F, FontStyle.Bold)
     c.Font = nf
     c.Text = "This is" &_
     "12-point Arial bold"
   End Using
   End Sub

4. Explicit Zero Lower Bound on an Array, Visual Basic now permits an array declaration to specify the lower bound (0) of each dimension along with the upper bound.
5. Unsigned Types, Visual Basic now supports unsigned integer data types (UShort, UInteger, and ULong) as well as the signed type SByte.
6. Operator Overloading, Visual Basic now allows you to define a standard operator (such as +, &, Not, or Mod) on a class or structure you have defined.
7. Partial Types, to separate generated code from your authored code into separate source files.
8. Visual Basic now supports type parameters on generic classes, structures, interfaces, procedures, and delegates. A corresponding type argument specifies at compilation time the data type of one of the elements in the generic type.
9. Custom Events. You can declare custom events by using the Custom keyword as a modifier for the Event statement. In a custom event, you specify exactly what happens when code adds or removes an event handler to or from the event, or when code raises the event.
10. Compiler Checking Options, The /nowarn and /warnaserror options provide more control over how warnings are handled. Each one of these compiler options now takes a list of warning IDs as an optional parameter, to specify to which warnings the option applies.
11. There are eight new command-line compiler options:
    1. The /codepage option specifies which codepage to use when opening source files.
    2. The /doc option generates an XML documentation file based on comments within your code.
    3. The /errorreport option provides a convenient way to report a Visual Basic internal compiler error to Microsoft.
    4. The /filealign option specifies the size of sections in your output file.
    5. The /noconfig option causes the compiler to ignore the Vbc.rsp file.
    6. The /nostdlib option prevents the import of mscorlib.dll, which defines the entire System namespace.
    7. The /platform option specifies the processor to be targeted by the output file, in those situations where it is necessary to explicitly specify it.
    8. The /unify option suppresses warnings resulting from a mismatch between the versions of directly and indirectly referenced assemblies.

With the release of Visual Studio 2005, the C# language has been updated to version 2.0. This language has following new features:

1. Generics types are added to the language to enable programmers to achieve a high level of code reuse and enhanced performance for collection classes. Generic types can differ only by arity. Parameters can also be forced to be specific types.
2. Iterators make it easier to dictate how a for each loop will iterate over a collection's contents.

   // Iterator Example
   public class NumChar
   {
   string[] saNum = { 
     "One", "Two", "Three", 
     "Four", "Five", "Six", 
     "Seven", "Eight", "Nine", 
     "Zero"};
   public 
    System.Collections.IEnumerator 
    GetEnumerator()
   {
   foreach (string num in saNum)
   yield return num;
   }
   }
   // Create an instance of 
   // the collection class
   NumChar oNumChar = new NumChar();
   // Iterate through it with foreach
   foreach (string num in oNumChar)
   Console.WriteLine(num);

3. Partial type definitions allow a single type, such as a class, to be split into multiple files. The Visual Studio designer uses this feature to separate its generated code from user code.
4. Nullable types allow a variable to contain a value that is undefined.
5. Anonymous Method is now possible to pass a block of code as a parameter. Anywhere a delegate is expected, a code block can be used instead: There is no need to define a new method.

   button1.Click += 
    delegate { MessageBox.Show( 
    "Click!") };

6. . The namespace alias qualifier (::) provides more control over accessing namespace members. The global :: alias allows to access the root namespace that may be hidden by an entity in your code.
7. Static classes are a safe and convenient way of declaring a class containing static methods that cannot be instantiated. In C# v1.2 you would have defined the class constructor as private to prevent the class being instantiated.
8. 8. There are eight new compiler options:
   1. /langversion option: Can be used to specify compatibility with a specific version of the language.
   2. /platform option: Enables you to target IPF (IA64 or Itanium) and AMD64 architectures.
   3. #pragma warning: Used to disable and enable individual warnings in code.
   4. /linkresource option: Contains additional options.
   5. /errorreport option: Can be used to report internal compiler errors to Microsoft over the Internet.
   6. /keycontainer and /keyfile: Support specifying cryptographic keys.