C#和VB.net语法对比图

C#和VB.net语法对比图
注释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 */
数据类型 Data Types
VB.NET          '值类型 Value Types Boolean Byte Char (example: "A") Short, Integer, Long Single, Double Decimal Date           '引用类型 Reference Types Object String Dim x As Integer System.Console.WriteLine(x.GetType()) System.Console.WriteLine(TypeName(x))   '类型转换 Type conversion Dim d As Single = 3.5 Dim i As Integer = CType(d, Integer) i = CInt(d) i = Int(d)	C#  //值类型 Value Types bool byte, sbyte char (example: ‘A‘) short, ushort, int, uint, long, ulong float, double decimal DateTime   //引用类型 Reference Types object string int x; Console.WriteLine(x.GetType()) Console.WriteLine(typeof(int)) //类型转换 Type conversion float d = 3.5; int i = (int) d
常量 Constants
VB.NET Const MAX_AUTHORS As Integer = 25 ReadOnly MIN_RANK As Single = 5.0	C# const int MAX_AUTHORS = 25; readonly float MIN_RANKING = 5.00f;
枚举 Enumerations
VB.NET   Enum Action         Start         'Stop是个关键字 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)   End If   'Prints 70   System.Console.WriteLine(Status.Pass)   'Prints Pass   System.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 70 System.Console.WriteLine((int)Status.Pass); // Prints Pass System.Console.WriteLine(Status.Pass);
操作符 Operators
VB.NET   '比较运算符 Comparison  =  <  >  <=  >=  <> '数学运算符 Arithmetic     +  -  *  /     Mod     /  (integer division)     ^  (raise to a power) '赋值运算符 Assignment     =  +=  -=  *=  /=  =  ^=  <<=  >>=  &= '按位运算符 Bitwise     And  AndAlso  Or  OrElse  Not  <<  >> '逻辑运算符 Logical     And  AndAlso  Or  OrElse  Not '字符串运算符 String Concatenation     &	C#   //比较运算符Comparison ==  <  >  <=  >=  != //数学运算符Arithmetic +  -  *  / %  (mod) /  (integer division if both operands are ints) Math.Pow(x, y) //赋值运算符 Assignment =  +=  -=  *=  /=   %=  &=  =  ^=  <<=  >>=  ++  -- //按位运算符 Bitwise &    ^   ~  <<  >> //逻辑运算符 Logical &&     ! //字符串运算符 String Concatenation +
选择语句 Choices
VB.NET   greeting = IIf(age < 20, "What‘s up?", "Hello")   '同一行不用”End If” 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; }
循环语句 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++;     //Post-test Loop: do   i++; while (i < 10);           for (i = 2; i < = 10; i += 2)   System.Console.WriteLine(i);   // Array or collection looping string[] names = {"Steven", "SuOk", "Sarah"}; foreach (string s in names)   System.Console.WriteLine(s);
数组 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] = 4.5f;   int[][] jagged = new int[3][] {   new int[5], new int[2], new int[3] }; jagged[0][4] = 5;
函数 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 1   'Optional parameters must be listed last 'and must have a default value Sub SayHello(ByVal name As String, Optional ByVal prefix As String = "")     Response.Write("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, ""); }
异常处理 Exception Handling
VB.NE  'Deprecated unstructured error handling On Error GoTo MyErrorHandler      DoSomething() MyErrorHandler: System.Console.WriteLine(Err.Description)   Dim ex As New Exception("Something has really gone wrong.") Throw ex   Try     y = 0     x = 10 / y Catch 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 }
命名空间 Namespaces
VB.NET  Namespace ASPAlliance.DotNet.Community     'Do something End Namespace 'or Namespace ASPAlliance     Namespace DotNet         Namespace Community                     'Do something         End Namespace     End Namespace End Namespace   Imports ASPAlliance.DotNet.Community	C#  namespace ASPAlliance.DotNet.Community {     //Do something } // or namespace ASPAlliance {   namespace DotNet {     namespace Community {     //Do something     }   } }   using ASPAlliance.DotNet.Community;
类/接口 Classes / Interfaces
VB.NET  'Accessibility keywords Public Private Friend Protected Protected Friend Shared   'Inheritance Class Articles     Inherits Authors             ' ... End Class 'Interface definition Interface IArticle     ' ... End Interface   'Extending an interface Interface IArticle     Inherits IAuthor     '... End Interface   'Interface implementation Class PublicationDate     Implements IArticle, IRating     '... End Class	C#  //Accessibility keywords public private internal protected protected internal static //Inheritance class Articles: Authors {   ... } //Interface definition interface IArticle {   //... } //Extending an interface interface IArticle: IAuthor {   //... } //Interface implementation class PublicationDate: IArticle, IRating {    //... }
构造函数/析构函数 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     } }
对象 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.");
结构体 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
属性 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	C# private int _size; public int Size {   get   {         return _size;   }   set   {     if (value < 0)       _size = 0;     else       _size = value;   } } foo.Size++;
代理/事件 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); }
输入输出 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"
文件输入输出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();