实例VB.NET常用代码归纳总结("VB.NET常用代码实例精华汇总")

一、基本语法与数据类型

在VB.NET编程中，掌握基本语法和数据类型是至关重要的。以下是一些常用的代码实例。

1. 数据类型声明

Dim a As Integer = 10
Dim b As Double = 3.14
Dim c As String = "Hello, World!"
Dim d As Boolean = True

2. 变量赋值

a = 20
b = 2.718
c = "VB.NET"
d = False

二、控制结构

控制结构是程序设计中不可或缺的部分，以下是一些常用的控制结构代码实例。

1. 条件语句

If a > 10 Then
    Console.WriteLine("a 大于 10")
ElseIf a < 10 Then
    Console.WriteLine("a 小于 10")
Else
    Console.WriteLine("a 等于 10")
End If

2. 循环语句

For i As Integer = 1 To 10
    Console.WriteLine(i)
Next
For Each item As String In c.Split(New Char() {" "c})
    Console.WriteLine(item)
Next
Do While a > 0
    Console.WriteLine(a)
    a -= 1
Loop
Do
    Console.WriteLine(a)
    a -= 1
Loop While a > 0

三、函数与过程

函数与过程是VB.NET编程中实现模块化设计的重要手段，以下是一些常用的代码实例。

1. 函数定义与调用

Function AddNumbers(x As Integer, y As Integer) As Integer
    Return x + y
End Function
Dim result As Integer = AddNumbers(5, 10)
Console.WriteLine("最终：" & result)

2. 过程定义与调用

Sub PrintMessage(message As String)
    Console.WriteLine(message)
End Sub
PrintMessage("Hello, World!")

四、面向对象编程

面向对象编程是现代编程的核心思想，以下是一些常用的代码实例。

1. 类的定义与实例化

Class Person
    Public Property Name As String
    Public Property Age As Integer
    Public Sub New(name As String, age As Integer)
        Me.Name = name
        Me.Age = age
    End Sub
    Public Sub SayHello()
        Console.WriteLine("你好，我是" & Name & "，今年" & Age & "岁。")
    End Sub
End Class
Dim person As New Person("张三", 25)
person.SayHello()

2. 继承与多态

Class Student
    Inherits Person
    Public Property School As String
    Public Sub New(name As String, age As Integer, school As String)
        MyBase.New(name, age)
        Me.School = school
    End Sub
    Public Overrides Sub SayHello()
        Console.WriteLine("你好，我是" & Name & "，今年" & Age & "岁，就读于" & School & "。")
    End Sub
End Class
Dim student As New Student("李四", 20, "北京大学")
student.SayHello()

五、文件操作

文件操作是编程中常见的需求，以下是一些常用的代码实例。

1. 文件读取

Dim filePath As String = "C:\example.txt"
Dim content As String = ""
If File.Exists(filePath) Then
    Using reader As New StreamReader(filePath)
        content = reader.ReadToEnd()
    End Using
End If
Console.WriteLine(content)

2. 文件写入

Dim filePath As String = "C:\example.txt"
Dim content As String = "Hello, World!"
Using writer As New StreamWriter(filePath, False)
    writer.WriteLine(content)
End Using

六、异常处理

异常处理是保证程序稳定运行的关键，以下是一些常用的代码实例。

1. Try-Catch语句

Try
    Dim result As Integer = Integer.Parse("abc")
Catch ex As FormatException
    Console.WriteLine("出现格式异常：" & ex.Message)
Catch ex As Exception
    Console.WriteLine("出现异常：" & ex.Message)
Finally
    Console.WriteLine("无论是否出现异常，都会执行这里的代码。")
End Try

2. 异常捕获与抛出

Sub TestException()
    Try
        Throw New Exception("自定义异常")
    Catch ex As Exception
        Console.WriteLine("捕获到异常：" & ex.Message)
    End Try
End Sub
TestException()

七、网络编程

网络编程是现代应用程序的重要功能，以下是一些常用的代码实例。

1. HTTP请求

Imports System.Net.Http
Dim client As New HttpClient()
Dim response As HttpResponseMessage = client.GetAsync("http://www.example.com").Result
Dim content As String = response.Content.ReadAsStringAsync().Result
Console.WriteLine(content)

2. Socket编程

Imports System.Net.Sockets
Dim tcpClient As New TcpClient()
tcpClient.Connect("www.example.com", 80)
Using stream As NetworkStream = tcpClient.GetStream()
    ' 发送HTTP请求
    Dim request As String = "GET / HTTP/1.1" & vbCrLf & "Host: www.example.com" & vbCrLf & "Connection: close" & vbCrLf & vbCrLf
    Dim buffer As Byte() = System.Text.Encoding.ASCII.GetBytes(request)
    stream.Write(buffer, 0, buffer.Length)
    ' 接收HTTP响应
    Dim responseBuffer As Byte() = New Byte(1023) {}
    Dim bytesRead As Integer = stream.Read(responseBuffer, 0, responseBuffer.Length)
    Dim response As String = System.Text.Encoding.ASCII.GetString(responseBuffer, 0, bytesRead)
    Console.WriteLine(response)
End Using
tcpClient.Close()

八、数据库操作

数据库操作是应用程序的核心功能之一，以下是一些常用的代码实例。

1. 连接数据库

Imports System.Data.SqlClient
Dim connectionString As String = "Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;"
Using connection As New SqlConnection(connectionString)
    connection.Open()
    Console.WriteLine("数据库连接圆满！")
End Using

2. 执行SQL语句

Using connection As New SqlConnection(connectionString)
    connection.Open()
    Using command As New SqlCommand("SELECT * FROM myTable", connection)
        Using reader As SqlDataReader = command.ExecuteReader()
            While reader.Read()
                Console.WriteLine(reader("ColumnName").ToString())
            End While
        End Using
    End Using
End Using

总结

VB.NET作为一种强劲的编程语言，拥有多彩的语法和功能。本文通过归纳总结常用的代码实例，旨在帮助开发者敏捷掌握VB.NET编程。在实际开发过程中，开发者还需逐步积累经验，灵活运用所学知识，以尽也许减少损耗编程水平。

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