VB C# 语法对比图 (代码实例)

Comments

VB.NET

'Single line onlyRem Single line only

C#

// Single line/* Multipleline *//// XML comments on single line/** XML comments on multiple lines */

Data Types

VB.NET

'Value TypesBooleanByteChar (example: "A")Short, Integer, LongSingle, DoubleDecimalDate 'Reference TypesObjectStringDim x As IntegerSystem.Console.WriteLine(x.GetType())System.Console.WriteLine(TypeName(x)) 'Type conversionDim d As Single = 3.5Dim i As Integer = CType (d, Integer)i = CInt (d)i = Int(d)

C#

//Value Typesboolbyte, sbytechar (example: 'A')short, ushort, int, uint, long, ulongfloat, doubledecimalDateTime //Reference Typesobjectstringint x;Console.WriteLine(x.GetType())Console.WriteLine(typeof(int)) //Type conversionfloat d = 3.5;int i = (int) d

Constants

VB.NET

Const MAX_AUTHORS As Integer = 25ReadOnly 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  ForwardEnd EnumEnum Status   Flunk = 50   Pass = 70   Excel = 90End EnumDim a As Action = Action.Stop If a <> Action.Start Then _'Prints "Stop is 1"    System.Console.WriteLine(a.ToString & " is " & a)'Prints 70System.Console.WriteLine(Status.Pass)'Prints PassSystem.Console.WriteLine(Status.Pass.ToString())

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 70System.Console.WriteLine((int) Status.Pass,',','); // Prints PassSystem.Console.WriteLine(Status.Pass,',',');

Operators

VB.NET

'Comparison=  <  >  <=  >=  <> 'Arithmetic+  -  *  /Mod  (integer division)^  (raise to a power) 'Assignment=  +=  -=  *=  /=  =  ^=  <<=  >>=  &= 'BitwiseAnd  AndAlso  Or  OrElse  Not  <<  >> 'LogicalAnd  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 lineIf x <> 100 And y < 5 Then x *= 5 : y *= 2   'PreferredIf x <> 100 And y < 5 Then  x *= 5  y *= 2End 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 -= yElse  x /= yEnd If 'Must be a primitive data typeSelect Case color     Case "black", "red"    r += 1  Case "blue"    b += 1  Case "green"    g += 1  Case Else    other += 1End 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 stringswitch (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 += 1End While Do Until c = 10  c += 1Loop 'Post-test Loop:Do While c < 10  c += 1Loop For c = 2 To 10 Step 2  System.Console.WriteLine(c)Next 'Array or collection loopingDim 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 loopingstring[] 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 elementsDim names(4) As Stringnames(0) = "Steven"'Throws System.IndexOutOfRangeExceptionnames(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) = 4.5Dim 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 arraystring[] names = new string[5];names[0] = "Steven";// Throws System.IndexOutOfRangeExceptionnames[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 = 5End Sub 'c set to zero by defaultDim a = 1, b = 1, c As IntegerTestFunc(a, b, c)System.Console.WriteLine("{0} {1} {2}", a, b, c) '1 2 5 'Accept variable number of argumentsFunction Sum(ByVal ParamArray nums As Integer()) As Integer  Sum = 0  For Each i As Integer In nums    Sum += i  NextEnd 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 valueSub SayHello(ByVal name As String,Optional ByVal prefix As String = "")  System.Console.WriteLine("Greetings, " & prefix& " " & name)End SubSayHello("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 initializingTestFunc(a, ref b, out c,',',');System.Console.WriteLine("{0} {1} {2}", a, b, c,',','); // 1 2 5 // Accept variable number of argumentsint 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

'Deprecated unstructured error handlingOn Error GoTo MyErrorHandler...MyErrorHandler: System.Console.WriteLine(Err.Description)Dim ex As New Exception("Something has really gone wrong.")Throw ex Try  y = 0  x = 10 / yCatch ex As Exception When y = 0 'Argument and When is optional  System.Console.WriteLine(ex.Message) Finally  DoSomething() End Try

C#

Exception up = new Exception("Something is really wrong.",',','); throw up; // ha ha try{  y = 0;  x = 10 / y;}catch (Exception ex) { //Argument is optional, no "When" keyword  Console.WriteLine(ex.Message,',',');}finally{  // Do something}

Namespaces

VB.NET

Namespace ASPAlliance.DotNet.Community  ...End Namespace 'or Namespace ASPAlliance   Namespace DotNet    Namespace Community      ...    End Namespace  End NamespaceEnd 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 keywordsPublicPrivateFriendProtectedProtected FriendShared 'InheritanceClass Articles  Inherits Authors  ...End Class 'Interface definitionInterface IArticle   ...End Interface 'Extending an interfaceInterface IArticle  Inherits IAuthor  ...End Interface 'Interface implementationClass PublicationDate  Implements IArticle, IRating   ...End Class

C#

//Accessibility keywordspublicprivateinternalprotectedprotected internalstatic //Inheritanceclass Articles: Authors {  ...} //Interface definitioninterface IArticle {  ...} //Extending an interfaceinterface IArticle: IAuthor {  ...} //Interface implementationclass PublicationDate: IArticle, IRating {   ...}

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 SubEnd 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 TopAuthorWith author  .Name = "Steven"  .AuthorRanking = 3End Withauthor.Rank("Scott")author.Demote() 'Calling Shared method'orTopAuthor.Rank() Dim author2 As TopAuthor = author 'Both refer to same objectauthor2.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 TopAuthorIf TypeOf obj Is TopAuthor Then _  System.Console.WriteLine("Is a TopAuthor object.")

C#

TopAuthor author = new TopAuthor(,',',');//No "With" constructauthor.Name = "Steven";author.AuthorRanking = 3; author.Rank("Scott",',',');TopAuthor.Demote() //Calling static method TopAuthor author2 = author //Both refer to same objectauthor2.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 SubEnd Structure Dim author As AuthorRecord = New AuthorRecord("Steven", 8.8)Dim author2 As AuthorRecord = authorauthor2.name = "Scott"System.Console.WriteLine(author.name) 'Prints StevenSystem.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 = authorauthor.name = "Scott";SystemConsole.WriteLine(author.name,',','); //Prints StevenSystem.Console.WriteLine(author2.name,',','); //Prints Scott

Properties

VB.NET

Private _size As IntegerPublic 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 SetEnd Property foo.Size += 1

C#

private int _size;public int Size {  get {    return _size;  }  set {    if (value < 0)      _size = 0;    else      _size = value;  }} foo.Size++;

Delegates / Events

VB.NET

Delegate Sub MsgArrivedEventHandler(ByVal messageAs String) Event MsgArrivedEvent As MsgArrivedEventHandler 'or to define an event which declares a'delegate implicitlyEvent MsgArrivedEvent(ByVal message As String) AddHandler MsgArrivedEvent, AddressOf My_MsgArrivedCallback'Won't throw an exception if obj is NothingRaiseEvent MsgArrivedEvent("Test message")RemoveHandler MsgArrivedEvent, AddressOf My_MsgArrivedCallbackImports System.Windows.Forms 'WithEvents can't be used on local variableDim WithEvents MyButton As ButtonMyButton = 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 nullMsgArrivedEvent("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 constantsvbCrLf, vbCr, vbLf, vbNewLinevbNullStringvbTabvbBackvbFormFeedvbVerticalTab""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)'orSystem.Console.WriteLine(name & " is " & age & " years old.")Dim c As Integerc = System.Console.Read() 'Read single charSystem.Console.WriteLine(c) 'Prints 65 if user enters "A"

C#

//Escape sequencesn, rt 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,',',');//orSystem.Console.WriteLine(name + " is " + 
 age + " years old.",',','); int c = System.Console.Read(,',','); //Read single charSystem.Console.WriteLine(c,',','); 
//Prints 65 if user enters "A"

File I/O

VB.NET

Imports System.IO 'Write out to text fileDim writer As StreamWriter = File.CreateText  ("c:myfile.txt")writer.WriteLine("Out to file.")writer.Close() 'Read all lines from text fileDim 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 Whilereader.Close() 'Write out to binary fileDim str As String = "Text data"Dim num As Integer = 123Dim binWriter As New BinaryWriter(File.OpenWrite  ("c:myfile.dat"))binWriter.Write(str)binWriter.Write(num)binWriter.Close() 'Read from binary fileDim 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 fileStreamWriter writer = File.CreateText  ("c:myfile.txt",',',');writer.WriteLine("Out to file.",',',');writer.Close(,',','); //Read all lines from text fileStreamReader 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 filestring 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 fileBinaryReader binReader = new BinaryReader(File.OpenRead  ("c:myfile.dat"),',',');str = binReader.ReadString(,',',');num = binReader.ReadInt32(,',',');binReader.Close(,',',');