vb.net与c#语法对比图

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vb.net与c#语法对比图

制作者：剑锋冷月单位：无忧统计网,www.51stat.net

　　C#和VB.net的语法相差还是比较大的. 可能你会C#,可能你会VB.

　　将它们俩放在一起对比一下你就会很快读懂,并掌握另一门语言.

　　相信下面这张图会对你帮助很大.

　　Comments

　　VB.NET

'Single line only

Rem Single line only

// 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)

//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

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 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

//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

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)

'Array or collection looping

Dim names As String() = {"Steven", "SuOk", "Sarah"}

For Each s As String In names

　System.Console.WriteLine(s)

//Pre-test Loops: while (i < 10)

　i++;

for (i = 2; i < = 10; i += 2)

　System.Console.WriteLine(i);

//Post-test Loop:

　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))

'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

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

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")

// 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'tsupport 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

　　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

Imports ASPAlliance.DotNet.Community

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

//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

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.")

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

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

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

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"

//Escape sequences

n, r

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()

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();

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