VB.NET and C# Comparison【转】

This document is an authorized derivative of Frank McCown's "VB.NET and C# Comparison" (C) 2005 at
http://www.harding.edu/USER/fmccown/WWW/vbnet_csharp_comparison.html

This work is licensed under a Create Common License

Comments
VB.NET 'Single line only Rem Single line only	C# // Single line /* Multiple line */ /// XML comments on single line /** XML comments on multiple lines */
Program Structure
VB.NET Imports System Namespace MyNameSpace   Class HelloWorld     'Entry point which delegates to C-style main Private Function     Public Overloads Shared Sub Main()       Main(System.Environment.GetCommandLineArgs())     End Sub   Overloads Shared Sub Main(args() As String)     System.Console.WriteLine("Hello World")   End Sub 'Main   End Class 'HelloWorld End Namespace 'MyNameSpace	C# using System Namespace MyNameSpace {   class HelloWorld   {          static void Main(string[] args)     {       System.Console.WriteLine("Hello World")     }   } }
Data Types
VB.NET 'Value Types Boolean Byte Char (example: "A") Short, Integer, Long Single, Double Decimal Date 'Reference Types Object String Dim x As Integer System.Console.WriteLine(x.GetType()) System.Console.WriteLine(TypeName(x)) 'Type conversion Dim d As Single = 3.5 Dim i As Integer = CType (d, Integer) i = CInt (d) i = Int(d)	C# //Value Types bool byte, sbyte char (example: 'A') short, ushort, int, uint, long, ulong float, double decimal DateTime //Reference Types object string int x; Console.WriteLine(x.GetType()) Console.WriteLine(typeof(int)) //Type conversion float d = 3.5; int i = (int) d
Constants
VB.NET Const MAX_AUTHORS As Integer = 25 ReadOnly MIN_RANK As Single = 5.00	C# const int MAX_AUTHORS = 25; readonly float MIN_RANKING = 5.00;
Enumerations
VB.NET Enum Action   Start   'Stop is a reserved word [Stop]   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 _ 'Prints "Stop is 1"    System.Console.WriteLine(a.ToString & " is " & a) 'Prints 70 System.Console.WriteLine(Status.Pass) 'Prints Pass System.Console.WriteLine(Status.Pass.ToString()) Enum Weekdays    Saturday    Sunday    Monday    Tuesday    Wednesday    Thursday    Friday End Enum 'Weekdays	C# enum Action {Start, Stop, Rewind, Forward}; enum Status {Flunk = 50, Pass = 70, Excel = 90}; Action a = Action.Stop; if (a != Action.Start) //Prints "Stop is 1"   System.Console.WriteLine(a + " is " + (int) a); // Prints 70 System.Console.WriteLine((int) Status.Pass); // Prints Pass System.Console.WriteLine(Status.Pass); enum Weekdays {   Saturday, Sunday, Monday, Tuesday, Wednesday, Thursday, Friday }
Operators
VB.NET 'Comparison =  <  >  <=  >=  <> 'Arithmetic + - * / Mod "  (integer division) ^  (raise to a power) 'Assignment =  +=  -=  *=  /=  "=  ^=  <<=  >>=  &= 'Bitwise And  AndAlso Or  OrElse Not  <<  >> 'Logical And AndAlso Or  OrElse  Not 'String Concatenation &	C# //Comparison ==  <  >  <=  >=  != //Arithmetic + - * / %  (mod) /  (integer division if both operands are ints) Math.Pow(x, y) //Assignment =  +=  -=  *=  /=   %=  &=  |=  ^=  <<=  >>=  ++  -- //Bitwise &  |  ^   ~  <<  >> //Logical &&  ||   ! //String Concatenation +
Choices
VB.NET greeting = IIf(age < 20, "What's up?", "Hello") 'One line doesn't require "End If", no "Else" If language = "VB.NET" Then langType = "verbose" '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 'or to break up any long single command use _ If henYouHaveAReally < 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 'Must be a primitive data type Select Case color     Case "black", "red"     r += 1  Case "blue"     b += 1  Case "green"     g += 1  Case Else     other += 1 End Select	C# greeting = age < 20 ? "What's up?" : "Hello"; if (x != 100 && y < 5) {  // Multiple statements must be enclosed in {}   x *= 5;   y *= 2; } if (x > 5)   x *= y; else if (x == 5)   x += y; else if (x < 10)   x -= y; else   x /= y; //Must be integer or string switch (color) {  case "black":  case "red":    r++;    break;  case "blue"    break;  case "green": g++;      break;  default:    other++;    break; }
Loops
VB.NET 'Pre-test Loops: While c < 10   c += 1 End While Do Until c = 10   c += 1 Loop 'Post-test Loop: Do While c < 10   c += 1 Loop For c = 2 To 10 Step 2   System.Console.WriteLine(c) Next 'Array or collection looping Dim names As String() = {"Steven", "SuOk", "Sarah"} For Each s As String In names   System.Console.WriteLine(s) Next	C# //Pre-test Loops: while (i < 10)   i++; for (i = 2; i < = 10; i += 2)   System.Console.WriteLine(i); //Post-test Loop: do   i++; while (i < 10); // Array or collection looping string[] names = {"Steven", "SuOk", "Sarah"}; foreach (string s in names)   System.Console.WriteLine(s);
Arrays
VB.NET 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) = "Steven" 'Throws System.IndexOutOfRangeException names(5) = "Sarah" '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	C# 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] = "Steven"; // Throws System.IndexOutOfRangeException names[5] = "Sarah" // C# can't dynamically resize an array. //Just copy into new array. string[] names2 = new string[7]; // or names.CopyTo(names2, 0); Array.Copy(names, names2, names.Length); float[,] twoD = new float[rows, cols]; twoD[2,0] = 4.5; int[][] jagged = new int[3][] {  new int[5], new int[2], new int[3] }; jagged[0][4] = 5;
Functions
VB.NET '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 'c set to zero by default Dim a = 1, b = 1, c As Integer TestFunc(a, b, c) System.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 a 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 = "")   System.Console.WriteLine("Greetings, " & prefix & " " & name) End Sub SayHello("Steven", "Dr.") SayHello("SuOk")	C# // 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); System.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) {   System.Console.WriteLine("Greetings, " + prefix + " " + name); } void SayHello(string name) {   SayHello(name, ""); }
Exception Handling
VB.NET Class Withfinally    Public Shared Sub Main()       Try          Dim x As Integer = 5          Dim y As Integer = 0          Dim z As Integer = x / y          Console.WriteLine(z)       Catch e As DivideByZeroException          System.Console.WriteLine("Error occurred")       Finally          System.Console.WriteLine("Thank you")       End Try    End Sub 'Main End Class 'Withfinally	C# class  Withfinally {  public static void Main()   {     try     {       int x = 5;       int y = 0;       int z = x/y;       Console.WriteLine(z);     }     catch(DivideByZeroException e)     {       System.Console.WriteLine("Error occurred");     }     finally     {       System.Console.WriteLine("Thank you");     }   } }
Namespaces
VB.NET Namespace ASPAlliance.DotNet.Community   ... End Namespace 'or Namespace ASPAlliance  Namespace DotNet     Namespace Community       ...     End Namespace  End Namespace End Namespace Imports ASPAlliance.DotNet.Community	C# namespace ASPAlliance.DotNet.Community {   ... } // or namespace ASPAlliance {  namespace DotNet {     namespace Community {       ...     }   } } using ASPAlliance.DotNet.Community;
Classes / Interfaces
VB.NET 'Accessibility keywords Public Private Friend Protected Protected Friend Shared 'Inheritance Class Articles  Inherits Authors   ... End Class Imports System Interface IArticle    Sub Show() End Interface 'IArticle  _ Class IAuthor    Implements IArticle        Public Sub Show()       System.Console.WriteLine("Show() method Implemented")    End Sub 'Show       'Entry point which delegates to C-style main Private Function    Public Overloads Shared Sub Main()       Main(System.Environment.GetCommandLineArgs())    End Sub          Overloads Public Shared Sub Main(args() As String)       Dim author As New IAuthor()       author.Show()    End Sub 'Main End Class 'IAuthor	C# //Accessibility keywords public private internal protected protected internal static //Inheritance class Articles: Authors {   ... } using System; interface IArticle {  void Show(); } class IAuthor:IArticle {  public void Show()   {     System.Console.WriteLine("Show() method Implemented");   }  public static void Main(string[] args)   {     IAuthor author = new IAuthor();     author.Show();   } }
Constructors / Destructors
VB.NET Class TopAuthor  Private _topAuthor As Integer  Public Sub New()     _topAuthor = 0  End Sub  Public Sub New(ByVal topAuthor As Integer)     Me._topAuthor = topAuthor  End Sub  Protected Overrides Sub Finalize()    'Desctructor code to free unmanaged resources     MyBase.Finalize()  End Sub End Class	C# class TopAuthor {  private int _topAuthor;  public TopAuthor() {      _topAuthor = 0;   }  public TopAuthor(int topAuthor) {     this._topAuthor= topAuthor   }   ~TopAuthor() {     // Destructor code to free unmanaged resources.     // Implicitly creates a Finalize method   } }
Objects
VB.NET Dim author As TopAuthor = New TopAuthor With author   .Name = "Steven"   .AuthorRanking = 3 End With author.Rank("Scott") author.Demote() 'Calling Shared method 'or TopAuthor.Rank() Dim author2 As TopAuthor = author 'Both refer to same object author2.Name = "Joe" System.Console.WriteLine(author2.Name) 'Prints Joe author = Nothing 'Free the object If author Is Nothing Then _   author = New TopAuthor Dim obj As Object = New TopAuthor If TypeOf obj Is TopAuthor Then _   System.Console.WriteLine("Is a TopAuthor object.")	C# TopAuthor author = new TopAuthor(); //No "With" construct author.Name = "Steven"; author.AuthorRanking = 3; author.Rank("Scott"); TopAuthor.Demote() //Calling static method TopAuthor author2 = author //Both refer to same object author2.Name = "Joe"; System.Console.WriteLine(author2.Name) //Prints Joe author = null //Free the object if (author == null)   author = new TopAuthor(); Object obj = new TopAuthor();  if (obj is TopAuthor)   SystConsole.WriteLine("Is a TopAuthor object.");
Structs
VB.NET Structure AuthorRecord  Public name As String  Public rank As Single  Public Sub New(ByVal name As String, ByVal rank As Single)     Me.name = name     Me.rank = rank  End Sub End Structure Dim author As AuthorRecord = New AuthorRecord("Steven", 8.8) Dim author2 As AuthorRecord = author author2.name = "Scott" System.Console.WriteLine(author.name) 'Prints Steven System.Console.WriteLine(author2.name) 'Prints Scott	C# struct AuthorRecord {  public string name;  public float rank;  public AuthorRecord(string name, float rank) {     this.name = name;     this.rank = rank;   } } AuthorRecord author = new AuthorRecord("Steven", 8.8); AuthorRecord author2 = author author.name = "Scott"; SystemConsole.WriteLine(author.name); //Prints Steven System.Console.WriteLine(author2.name); //Prints Scott
Properties
VB.NET 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 Imports System Class [Date]       Public Property Day() As Integer       Get          Return day       End Get       Set          day = value       End Set    End Property    Private day As Integer          Public Property Month() As Integer       Get          Return month       End Get       Set          month = value       End Set    End Property    Private month As Integer          Public Property Year() As Integer       Get          Return year       End Get       Set          year = value       End Set    End Property    Private year As Integer          Public Function IsLeapYear(year As Integer) As Boolean       Return(If year Mod 4 = 0 Then True Else False)    End Function 'IsLeapYear       Public Sub SetDate(day As Integer, month As Integer, year As Integer)       Me.day = day       Me.month = month       Me.year = year    End Sub 'SetDate End Class '[Date]	C# private int _size; public int Size {   get {     return _size;   }   set {     if (value < 0)       _size = 0;     else       _size = value;   } } foo.Size++; using System; class Date {     public int Day{         get {             return day;         }         set {             day = value;         }     }     int day;     public int Month{         get {             return month;         }         set {             month = value;         }     }     int month;     public int Year{         get {             return year;         }         set {             year = value;         }     }     int year;     public bool IsLeapYear(int year)     {         return year%4== 0 ? true: false;     }     public void SetDate (int day, int month, int year)     {         this.day   = day;         this.month = month;         this.year  = year;     } }
Delegates / Events
VB.NET 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 'WithEvents can't be used on local variable Dim WithEvents MyButton As Button 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	C# delegate void MsgArrivedEventHandler(string message); event MsgArrivedEventHandler MsgArrivedEvent; //Delegates must be used with events in C# MsgArrivedEvent += new MsgArrivedEventHandler   (My_MsgArrivedEventCallback); //Throws exception if obj is null MsgArrivedEvent("Test message"); 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); }
Console I/O
VB.NET 'Special character constants vbCrLf, vbCr, vbLf, vbNewLine vbNullString vbTab vbBack vbFormFeed vbVerticalTab "" Chr(65) 'Returns 'A' System.Console.Write("What's your name? ") Dim name As String = System.Console.ReadLine() System.Console.Write("How old are you? ") Dim age As Integer = Val(System.Console.ReadLine()) System.Console.WriteLine("{0} is {1} years old.", name, age) 'or System.Console.WriteLine(name & " is " & age & " years old.") Dim c As Integer c = System.Console.Read() 'Read single char System.Console.WriteLine(c) 'Prints 65 if user enters "A"	C# //Escape sequences "n, "r "t "" " Convert.ToChar(65) //Returns 'A' - equivalent to Chr(num) in VB // or (char) 65 System.Console.Write("What's your name? "); string name = SYstem.Console.ReadLine(); System.Console.Write("How old are you? "); int age = Convert.ToInt32(System.Console.ReadLine()); System.Console.WriteLine("{0} is {1} years old.", name, age); //or System.Console.WriteLine(name + " is " + age + " years old."); int c = System.Console.Read(); //Read single char System.Console.WriteLine(c); //Prints 65 if user enters "A"
File I/O
VB.NET 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()	C# 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();