VB与C#的区别

一、实体部分

c#实体
public int Id //作用方式
{
get id;//读取属性值
set id;//设置属性值
}
public int Name
{
get name;
set name;
}

vb实体
Private ID As String '定义静态属性
Public Property ID() As String
Get
Return ID '作用：获取属性值
End Get
Set(value As String)
ID = value '作用：设置属性值
End Set
End Property

二、方法（函数）
C#的方法：语法格式为
//语法：访问限制符 返回值类型 方法名（参数[实体的实例]）
public void Modify(Login.Model.UserInfo user)
{
//方法体
}

VB.NET的方法：语法格式为
'语法：访问限制符 函数关键字 函数名（参数[ByVal 实体对象实例]）As 返回值类型
Public Function UserLogon(ByVal User As Entity.LogonEntity) As Entity.LogonEntity
Dim user1 As New Entity.LogonEntity
'方法体
Return user1
End Function

根据上面的实体与方法，可知c#与vb注释的方式也不一样，c#注释://或///，vb注释:‘

以下引用于https://blog.csdn.net/minsenwu/article/details/7615210
VB.NET
Program Structure
C#
Imports System

        Namespace Hello
           Class HelloWorld 
              Overloads Shared Sub Main(ByVal args() As String) 
                 Dim name As String = "VB.NET" 

                 'See if an argument was passed from the command line
                  If args.Length = 1 Then name = args(0) 

                  Console.WriteLine("Hello, " & name & "!") 
              End Sub 
           End Class 
        End Namespace

using System;

        namespace Hello {
           public class HelloWorld {
              public static void Main(string[] args) {
                 string name = "C#";

                 // See if an argument was passed from the command line
                 if (args.Length == 1)
                    name = args[0];

                 Console.WriteLine("Hello, " + name + "!");
              }
           }
        }

VB.NET
Comments
C#
’ Single line only
Rem Single line only
// Single line
/* Multiple
line /
/// XML comments on single line
/* XML comments on multiple lines */
VB.NET
Data Types
C#
Value Types
Boolean
Byte
Char (example: "A"c)
Short, Integer, Long
Single, Double
Decimal
Date
Reference Types
Object
String
Dim x As Integer
Console.WriteLine(x.GetType()) ’ Prints System.Int32
Console.WriteLine(GetType(Integer)) ’ Prints System.Int32
Console.WriteLine(TypeName(x)) ’ Prints Integer
’ Type conversion
Dim d As Single = 3.5
Dim i As Integer = CType(d, Integer) ’ set to 4 (Banker’s rounding)
i = CInt(d) ’ same result as CType
i = Int(d) ’ set to 3 (Int function truncates the decimal)
Value Types
bool
byte, sbyte
char (example: ‘A’)
short, ushort, int, uint, long, ulong
float, double
decimal
DateTime (not a built-in C# type)
Reference Types
object
string
int x;
Console.WriteLine(x.GetType()); // Prints System.Int32
Console.WriteLine(typeof(int)); // Prints System.Int32
Console.WriteLine(x.GetType().Name); // prints Int32

// Type conversion
float d = 3.5f;
int i = (int)d; // set to 3 (truncates decimal)
VB.NET
Constants
C#
Const MAX_STUDENTS As Integer = 25
’ Can set to a const or var; may be initialized in a constructor
ReadOnly MIN_DIAMETER As Single = 4.93
const int MAX_STUDENTS = 25;
// Can set to a const or var; may be initialized in a constructor
readonly float MIN_DIAMETER = 4.93f;
VB.NET
Enumerations
C#
Enum Action
Start
[Stop] ’ Stop is a reserved word
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 _ 
           Console.WriteLine(a.ToString & " is " & a)     ' Prints "Stop is 1"

        Console.WriteLine(Status.Pass)     ' Prints 70 
        Console.WriteLine(Status.Pass.ToString())     ' Prints Pass

enum Action {Start, Stop, Rewind, Forward};
enum Status {Flunk = 50, Pass = 70, Excel = 90};

        Action a = Action.Stop;
        if (a != Action.Start)
          Console.WriteLine(a + " is " + (int) a);    // Prints "Stop is 1"

        Console.WriteLine((int) Status.Pass);    // Prints 70 
        Console.WriteLine(Status.Pass);      // Prints Pass

VB.NET
Operators
C#
Comparison
= < > <= >= <>
Arithmetic
+ - * /
Mod
" (integer division)
^ (raise to a power)
Assignment
= += -= *= /= "= ^= <<= >>= &=
Bitwise
And Or Not << >>
Logical
AndAlso OrElse And Or Xor Not
Note: AndAlso and OrElse perform short-circuit logical evaluations
String Concatenation
& +
Comparison
== < > <= >= !=
Arithmetic
+ - * /
% (mod)
/ (integer division if both operands are ints)
Math.Pow(x, y)
Assignment
= += -= *= /= %= &= |= ^= <<= >>= ++ –
Bitwise
& | ^ ~ << >>
Logical
&& || & | ^ !
Note: && and || perform short-circuit logical evaluations
String Concatenation
+
VB.NET
Choices
C#
greeting = IIf(age < 20, “What’s up?”, “Hello”)
’ One line doesn’t require “End If”
If age < 20 Then greeting = “What’s up?”
If age < 20 Then greeting = “What’s up?” Else greeting = “Hello”
’ 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
’ To break up any long single line use _
If whenYouHaveAReally < 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
Select Case color ’ Must be a primitive data type
Case “pink”, “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 (age < 20)
greeting = “What’s up?”;
else
greeting = “Hello”;
// Multiple statements must be enclosed in {}
if (x != 100 && y < 5) {
x *= 5;
y *= 2;
}
No need for _ or : since ; is used to terminate each statement.

if (x > 5)
x *= y;
else if (x == 5)
x += y;
else if (x < 10)
x -= y;
else
x /= y;

// Every case must end with break or goto case
switch (color) { // Must be integer or string
case “pink”:
case “red”: r++; break;
case “blue”: b++; break;
case “green”: g++; break;
default: other++; break; // break necessary on default
}
VB.NET
Loops
C#
Pre-test Loops:
While c < 10
c += 1
End While
Do Until c = 10
c += 1
Loop
Do While c < 10
c += 1
Loop
For c = 2 To 10 Step 2
Console.WriteLine©
Next

Post-test Loops:
Do
c += 1
Loop While c < 10
Do
c += 1
Loop Until c = 10
’ Array or collection looping
Dim names As String() = {“Fred”, “Sue”, “Barney”}
For Each s As String In names
Console.WriteLine(s)
Next
’ Breaking out of loops
Dim i As Integer = 0
While (True)
If (i = 5) Then Exit While
i += 1
End While

’ Continue to next iteration
For i = 0 To 4
If i < 4 Then Continue For
Console.WriteLine(i) ’ Only prints 4
Next
Pre-test Loops:
// no “until” keyword
while (c < 10)
c++;

for (c = 2; c <= 10; c += 2)
Console.WriteLine©;

Post-test Loop:

do
c++;
while (c < 10);

// Array or collection looping
string[] names = {“Fred”, “Sue”, “Barney”};
foreach (string s in names)
Console.WriteLine(s);
// Breaking out of loops
int i = 0;
while (true) {
if (i == 5)
break;
i++;
}
// Continue to next iteration
for (i = 0; i < 5; i++) {
if (i < 4)
continue;
Console.WriteLine(i); // Only prints 4
}
VB.NET
Arrays
C#
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) = “David”
names(5) = “Bobby” ’ Throws System.IndexOutOfRangeException

’ 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] = “David”;
names[5] = “Bobby”; // Throws System.IndexOutOfRangeException

// C# can’t dynamically resize an array. Just copy into new array.
string[] names2 = new string[7];
Array.Copy(names, names2, names.Length); // or names.CopyTo(names2, 0);
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;
VB.NET
Functions
C#
’ 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
Dim a = 1, b = 1, c As Integer ’ c set to zero by default
TestFunc(a, b, c)
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 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 = “”)
Console.WriteLine("Greetings, " & prefix & " " & name)
End Sub

        SayHello("Strangelove", "Dr.")
        SayHello("Madonna")

// 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);
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) {
Console.WriteLine("Greetings, " + prefix + " " + name);
}

        void SayHello(string name) { 
          SayHello(name, ""); 
        }

VB.NET
Strings
C#
Special character constants
vbCrLf, vbCr, vbLf, vbNewLine
vbNullString
vbTab
vbBack
vbFormFeed
vbVerticalTab
“”
’ String concatenation (use & or +)
Dim school As String = “Harding” & vbTab
school = school & “University” ’ school is “Harding (tab) University”
’ Chars
Dim letter As Char = school.Chars(0) ’ letter is H
letter = Convert.ToChar(65) ’ letter is A
letter = Chr(65) ’ same thing
Dim word() As Char = school.ToCharArray() ’ word holds Harding
’ No string literal operator
Dim msg As String = "File is c:“temp"x.dat”

’ String comparison
Dim mascot As String = “Bisons”
If (mascot = “Bisons”) Then ’ true
If (mascot.Equals(“Bisons”)) Then ’ true
If (mascot.ToUpper().Equals(“BISONS”)) Then ’ true
If (mascot.CompareTo(“Bisons”) = 0) Then ’ true
Console.WriteLine(mascot.Substring(2, 3)) ’ Prints “son”
’ String matching
If (“John 3:16” Like “Jo[Hh]? #?”) Then 'true

        Imports System.Text.RegularExpressions   ' More powerful than Like
        Dim r As New Regex("Jo[hH]. "d:*")
        If (r.Match("John 3:16").Success) Then   'true

’ My birthday: Oct 12, 1973
Dim dt As New DateTime(1973, 10, 12)
Dim s As String = "My birthday: " & dt.ToString(“MMM dd, yyyy”)
’ Mutable string
Dim buffer As New System.Text.StringBuilder("two ")
buffer.Append("three ")
buffer.Insert(0, "one ")
buffer.Replace(“two”, “TWO”)
Console.WriteLine(buffer) ’ Prints “one TWO three”
Escape sequences
"n, "r
"t
“”
“”

// String concatenation
string school = “Harding"t”;
school = school + “University”; // school is “Harding (tab) University”
// Chars
char letter = school[0]; // letter is H
letter = Convert.ToChar(65); // letter is A
letter = (char)65; // same thing
char[] word = school.ToCharArray(); // word holds Harding
// String literal
string msg = @"File is c:“temp"x.dat”;
// same as
string msg = “File is c:”“temp”“x.dat”;
// String comparison
string mascot = “Bisons”;
if (mascot == “Bisons”) // true
if (mascot.Equals(“Bisons”)) // true
if (mascot.ToUpper().Equals(“BISONS”)) // true
if (mascot.CompareTo(“Bisons”) == 0) // true
Console.WriteLine(mascot.Substring(2, 3)); // Prints “son”
// String matching
// No Like equivalent - use regular expressions

        using System.Text.RegularExpressions;

Regex r = new Regex(@"Jo[hH]. “d:*”);
if (r.Match(“John 3:16”).Success) // true
// My birthday: Oct 12, 1973
DateTime dt = new DateTime(1973, 10, 12);
string s = "My birthday: " + dt.ToString(“MMM dd, yyyy”);
// Mutable string
System.Text.StringBuilder buffer = new System.Text.StringBuilder("two ");
buffer.Append("three ");
buffer.Insert(0, "one ");
buffer.Replace(“two”, “TWO”);
Console.WriteLine(buffer); // Prints “one TWO three”
VB.NET
Exception Handling
C#
’ Throw an exception
Dim ex As New Exception(“Something is really wrong.”)
Throw ex
’ Catch an exception
Try
y = 0
x = 10 / y
Catch ex As Exception When y = 0 ’ Argument and When is optional
Console.WriteLine(ex.Message)
Finally
Beep()
End Try
’ Deprecated unstructured error handling
On Error GoTo MyErrorHandler
…
MyErrorHandler: Console.WriteLine(Err.Description)
// Throw an exception
Exception up = new Exception(“Something is really wrong.”);
throw up; // ha ha
// Catch an exception
try {
y = 0;
x = 10 / y;
}
catch (Exception ex) { // Argument is optional, no “When” keyword
Console.WriteLine(ex.Message);
}
finally {
// Requires reference to the Microsoft.VisualBasic.dll
// assembly (pre .NET Framework v2.0)
Microsoft.VisualBasic.Interaction.Beep();
}
VB.NET
Namespaces
C#
Namespace Harding.Compsci.Graphics
…
End Namespace
’ or
Namespace Harding
Namespace Compsci
Namespace Graphics
…
End Namespace
End Namespace
End Namespace
Imports Harding.Compsci.Graphics
namespace Harding.Compsci.Graphics {
…
}
// or
namespace Harding {
namespace Compsci {
namespace Graphics {
…
}
}
}
using Harding.Compsci.Graphics;
VB.NET
Classes / Interfaces
C#
Accessibility keywords
Public
Private
Friend
Protected
Protected Friend
Shared
’ Inheritance
Class FootballGame
Inherits Competition
…
End Class
’ Interface definition
Interface IAlarmClock
…
End Interface
// Extending an interface
Interface IAlarmClock
Inherits IClock
…
End Interface
// Interface implementation
Class WristWatch
Implements IAlarmClock, ITimer
…
End Class
Accessibility keywords
public
private
internal
protected
protected internal
static
// Inheritance
class FootballGame : Competition {
…
}

// Interface definition
interface IAlarmClock {
…
}
// Extending an interface
interface IAlarmClock : IClock {
…
}

// Interface implementation
class WristWatch : IAlarmClock, ITimer {
…
}
VB.NET
Constructors / Destructors
C#
Class SuperHero
Private _powerLevel As Integer

          Public Sub New() 
            _powerLevel = 0 
          End Sub 

          Public Sub New(ByVal powerLevel As Integer) 
            Me._powerLevel = powerLevel 
          End Sub

          Protected Overrides Sub Finalize() 
           ' Desctructor code to free unmanaged resources 
            MyBase.Finalize() 
          End Sub

End Class
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
          }
        }

VB.NET
Using Objects
C#
Dim hero As SuperHero = New SuperHero
’ or
Dim hero As 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 reference the same object
hero2.Name = “WormWoman”
Console.WriteLine(hero.Name) ’ Prints WormWoman
hero = Nothing ’ Free the object
If hero IsNothing Then _
hero = New SuperHero
Dim obj As Object = New SuperHero
If TypeOf obj Is SuperHero Then _
Console.WriteLine(“Is a SuperHero object.”)
’ Mark object for quick disposal
Using reader As StreamReader = File.OpenText(“test.txt”)
Dim line As String = reader.ReadLine()
While Not line Is Nothing
Console.WriteLine(line)
line = reader.ReadLine()
End While
End Using
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 reference the 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.”);
// Mark object for quick disposal
using (StreamReader reader = File.OpenText(“test.txt”)) {
string line;
while ((line = reader.ReadLine()) != null)
Console.WriteLine(line);
}
VB.NET
Structs
C#
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

struct StudentRecord {
public string name;
public float gpa;

          public StudentRecord(string name, float gpa) {
            this.name = name;
            this.gpa = gpa;
          }
        }

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

VB.NET
Properties
C#
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++;

VB.NET
Delegates / Events
C#
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);
}
VB.NET
Console I/O
C#
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"

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"

VB.NET
File I/O
C#
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();