Comparison between Visual Basic and C#

Introduction

Some people like VB.NET's natural language, case-insensitive approach, others like C#'s terse syntax. But both have access to the same framework libraries. We will discuss about the differences in the following topics:

1. Advantages of both languages

2. Keyword Differences

3. Data types Differences

4. Operators Differences

5. Programming Difference

Advantages of both languages

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 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. 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.

Keyword Differences

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 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	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 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 Catch Finally 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 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	use Platform Invoke
Declare and raise an event	Event, RaiseEvent	event
Threading primitives	SyncLock	lock
Go to	Goto	goto

Data types Differences

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

Operators Differences

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)

Programming Difference

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 <> ' Same as n = n + 1. n += 1 End While '	while (n <> 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);

New Features of both languages in 2005 version

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, Continue Statement, which immediately skips to the next iteration of a Do, For, or Whileloop. IsNot operator, which you can avoid using the Not and Is operators in an awkward order. 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 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. Unsigned Types, Visual Basic now supports unsigned integer data types (UShort,UInteger, and ULong) as well as the signed type SByte. 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. Partial Types, to separate generated code from your authored code into separate source files. 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. 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. 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. There are eight new command-line compiler options: The /codepage option specifies which codepage to use when opening source files. The /doc option generates an XML documentation file based on comments within your code. The /errorreport option provides a convenient way to report a Visual Basic internal compiler error to Microsoft. The /filealign option specifies the size of sections in your output file. The /noconfig option causes the compiler to ignore the Vbc.rsp file. The /nostdlib option prevents the import of mscorlib.dll, which defines the entire System namespace. The /platform option specifies the processor to be targeted by the output file, in those situations where it is necessary to explicitly specify it. 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: 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. 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); 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. Nullable types allow a variable to contain a value that is undefined. 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!") }; . 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. 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. There are eight new compiler options: /langversion option: Can be used to specify compatibility with a specific version of the language. /platform option: Enables you to target IPF (IA64 or Itanium) and AMD64 architectures. #pragma warning: Used to disable and enable individual warnings in code. /linkresource option: Contains additional options. /errorreport option: Can be used to report internal compiler errors to Microsoft over the Internet. /keycontainer and /keyfile: Support specifying cryptographic keys.