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        • vb.net教程之C#和VB.net語法對比圖

        • 2019-06-19 22:12 來源:未知

        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 */
         
        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())
         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);
         
        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

         

        'Deprecated unstructured error handling
        On 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 / 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
        }
         
         
        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


        'Interface definition
        Interface IArticle 
          ...
        End Interface


        'Extending an interface
        Interface IArticle
          Inherits IAuthor
          ...
        End Interface


        'Interface implementation</span>
        Class PublicationDate
          Implements</strong> 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 {
           ...
        }
         
         
        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
         
         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 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#

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