VB.NET and C# 语法比较手册

class SuperHero {
  private int _powerLevel;

  public SuperHero() {
     _powerLevel = 0;
  }

  public SuperHero(int powerLevel) {
    this._powerLevel= powerLevel; 
  }

  ~SuperHero() {
    // Destructor code to free unmanaged resources.
    // Implicitly creates a Finalize method
  }
}

Dim hero As SuperHero = New SuperHero
With hero
  .Name = "SpamMan"
  .PowerLevel = 3
End With

hero.Defend("Laura Jones")
hero.Rest()     '''' Calling Shared method
'''' or
SuperHero.Rest()

Dim hero2 As SuperHero = hero  '''' Both refer to same object
hero2.Name = "WormWoman"
Console.WriteLine(hero.Name)   '''' Prints WormWoman

hero = Nothing    '''' Free the object

If hero Is Nothing Then _
  hero = New SuperHero

Dim obj As Object = New SuperHero
If TypeOf obj Is SuperHero Then _
  Console.WriteLine("Is a SuperHero object.")

SuperHero hero = new SuperHero();

// No "With" construct
hero.Name = "SpamMan";
hero.PowerLevel = 3;

hero.Defend("Laura Jones");
SuperHero.Rest();   // Calling static method

SuperHero hero2 = hero;   // Both refer to same object
hero2.Name = "WormWoman";
Console.WriteLine(hero.Name);   // Prints WormWoman

hero = null ;   // Free the object

if (hero == null)
  hero = new SuperHero();

Object obj = new SuperHero(); 
if (obj is SuperHero)
  Console.WriteLine("Is a SuperHero object.");

Structure StudentRecord
  Public name As String
  Public gpa As Single

  Public Sub New(ByVal name As String, ByVal gpa As Single)
    Me.name = name
    Me.gpa = gpa
  End Sub
End Structure

Dim stu As StudentRecord = New StudentRecord("Bob", 3.5)
Dim stu2 As StudentRecord = stu  

stu2.name = "Sue"
Console.WriteLine(stu.name)    '''' Prints Bob
Console.WriteLine(stu2.name)  '''' Prints Sue

StudentRecord stu = new StudentRecord("Bob", 3.5f);
StudentRecord stu2 = stu;  

stu2.name = "Sue";
Console.WriteLine(stu.name);    // Prints Bob
Console.WriteLine(stu2.name);   // Prints Sue

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

foo.Size++;

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

Dim WithEvents MyButton As Button   '''' WithEvents can''''t be used on local variable
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);
MsgArrivedEvent("Test message");    // Throws exception if obj is null
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);
}

Special character constants
vbCrLf, vbCr, vbLf, vbNewLine
vbNullString
vbTab
vbBack
vbFormFeed
vbVerticalTab
""
Chr(65)  '''' Returns ''''A''''

Console.Write("What''''s your name? ")
Dim name As String = Console.ReadLine()
Console.Write("How old are you? ")
Dim age As Integer = Val(Console.ReadLine())
Console.WriteLine("{0} is {1} years old.", name, age) 
'''' or
Console.WriteLine(name & " is " & age & " years old.")

Dim c As Integer
c = Console.Read()    '''' Read single char
Console.WriteLine(c)   '''' Prints 65 if user enters "A"

Escape sequences
\n, \r
\t
\\
\"

Convert.ToChar(65)  // Returns ''''A'''' - equivalent to Chr(num) in VB
// or
(char) 65

Console.Write("What''''s your name? ");
string name = Console.ReadLine();
Console.Write("How old are you? ");
int age = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("{0} is {1} years old.", name, age);
// or
Console.WriteLine(name + " is " + age + " years old.");

int c = Console.Read();  // Read single char
Console.WriteLine(c);    // Prints 65 if user enters "A"

Imports System.IO

Dim writer As StreamWriter = File.CreateText("c:\myfile.txt")
writer.WriteLine("Out to file.")
writer.Close()

Dim reader As StreamReader = File.OpenText("c:\myfile.txt")
Dim line As String = reader.ReadLine()
While Not line Is Nothing
  Console.WriteLine("line=" & line)
  line = reader.ReadLine()
End While
reader.Close()

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()

Dim binReader As New BinaryReader (File.OpenRead("c:\myfile.dat"))
str = binReader.ReadString()
num = binReader.ReadInt32()
binReader.Close()

using System.IO;

StreamWriter writer = File.CreateText("c:\\myfile.txt");
writer.WriteLine("Out to file.");
writer.Close();

StreamReader reader = File.OpenText("c:\\myfile.txt");
string line = reader.ReadLine();
while (line != null) {
  Console.WriteLine(line);
  line = reader.ReadLine();
}
reader.Close();

string str = "Text data";
int num = 123;
BinaryWriter binWriter = new BinaryWriter(File.OpenWrite("c:\\myfile.dat"));
binWriter.Write(str);
binWriter.Write(num);
binWriter.Close();

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