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273 lines
11 KiB
Markdown
273 lines
11 KiB
Markdown
---
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language: Visual Basic
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contributors:
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- ["Brian Martin", "http://brianmartin.biz"]
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translators:
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- ["Abner Chou", "http://github.com/NoahDragon"]
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lang: zh-cn
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filename: learnvisualbasic.vb-cn
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---
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```vb
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Module Module1
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Sub Main()
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' 让我们先从简单的终端程序学起。
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' 单引号用来生成注释（注意是半角单引号，非全角单引好’）
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' 为了方便运行此示例代码，我写了个目录索引。
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' 可能你还不了解以下代码的意义，但随着教程的深入，你会
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' 渐渐理解其用法。
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Console.Title = ("Learn X in Y Minutes")
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Console.WriteLine("NAVIGATION") ' 显示目录
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Console.WriteLine("")
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Console.ForegroundColor = ConsoleColor.Green
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Console.WriteLine("1. Hello World Output") ' Hello world 输出示例
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Console.WriteLine("2. Hello World Input") ' Hello world 输入示例
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Console.WriteLine("3. Calculating Whole Numbers") ' 求整数之和
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Console.WriteLine("4. Calculating Decimal Numbers") ' 求小数之和
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Console.WriteLine("5. Working Calculator") ' 计算器
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Console.WriteLine("6. Using Do While Loops") ' 使用 do while 循环
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Console.WriteLine("7. Using For While Loops") ' 使用 for while 循环
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Console.WriteLine("8. Conditional Statements") ' 条件语句
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Console.WriteLine("9. Select A Drink") ' 买饮料
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Console.WriteLine("50. About") ' 关于
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Console.WriteLine("Please Choose A Number From The Above List")
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Dim selection As String = Console.ReadLine
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Select Case selection
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Case "1" ' Hello world 输出示例
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Console.Clear() ' 清空屏幕
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HelloWorldOutput() ' 调用程序块
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Case "2" ' Hello world 输入示例
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Console.Clear()
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HelloWorldInput()
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Case "3" ' 求整数之和
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Console.Clear()
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CalculatingWholeNumbers()
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Case "4" ' 求小数之和
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Console.Clear()
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CalculatingDecimalNumbers()
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Case "5" ' 计算器
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Console.Clear()
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WorkingCalculator()
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Case "6" ' 使用 do while 循环
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Console.Clear()
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UsingDoWhileLoops()
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Case "7" ' 使用 for while 循环
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Console.Clear()
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UsingForLoops()
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Case "8" ' 条件语句
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Console.Clear()
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ConditionalStatement()
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Case "9" ' If/Else 条件语句
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Console.Clear()
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IfElseStatement() ' 选饮料
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Case "50" ' 关于
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Console.Clear()
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Console.Title = ("Learn X in Y Minutes :: About")
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MsgBox("This tutorial is by Brian Martin (@BrianMartinn")
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Console.Clear()
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Main()
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Console.ReadLine()
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End Select
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End Sub
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' 一、对应程序目录1，下同
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' 使用 private subs 来区分程序块.
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Private Sub HelloWorldOutput()
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' 程序名
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Console.Title = "Hello World Ouput | Learn X in Y Minutes"
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' 使用 Console.Write("") 或者 Console.WriteLine("") 来输出文本到屏幕上
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' 对应的 Console.Read() 或 Console.Readline() 用来读取键盘输入
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Console.WriteLine("Hello World")
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Console.ReadLine()
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End Sub
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' 二
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Private Sub HelloWorldInput()
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Console.Title = "Hello World YourName | Learn X in Y Minutes"
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' 变量
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' 用来存储用户输入的数据
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' 变量声明以 Dim 开始，结尾为 As VariableType （变量类型）.
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' 此教程中，我们希望知道你的姓名，并让程序记录并输出。
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Dim username As String
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' 我们使用字符串类型（String）来记录文本信息。
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Console.WriteLine("Hello, What is your name? ") ' 询问用户输入姓名
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username = Console.ReadLine() 'Stores the users name.
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Console.WriteLine("Hello " + username) ' 输出将是 Hello '姓名'
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Console.ReadLine() 'Outsputs the above.
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' 以上程序将询问你的姓名，并和你打招呼。
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' 其它变量如整型（Integer）我们用整型来处理整数。
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End Sub
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' 三
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Private Sub CalculatingWholeNumbers()
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Console.Title = "Calculating Whole Numbers | Learn X in Y Minutes"
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Console.Write("First number: ") ' 输入一个整数：1，2，50，104，等等
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Dim a As Integer = Console.ReadLine()
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Console.Write("Second number: ") ' 输入第二个整数
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Dim b As Integer = Console.ReadLine()
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Dim c As Integer = a + b
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Console.WriteLine(c)
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Console.ReadLine()
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' 以上程序将两个整数相加
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End Sub
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' 四
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Private Sub CalculatingDecimalNumbers()
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Console.Title = "Calculating with Double | Learn X in Y Minutes"
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' 当然，我们还需要能够处理小数。
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' 只需要要将整型（Integer）改为小数（Double）类型即可。
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' 输入一个小数： 1.2， 2.4， 50.1， 104.9，等等
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Console.Write("First number: ")
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Dim a As Double = Console.ReadLine
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Console.Write("Second number: ") ' 输入第二个数
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Dim b As Double = Console.ReadLine
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Dim c As Double = a + b
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Console.WriteLine(c)
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Console.ReadLine()
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' 以上代码能实现两个小数相加
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End Sub
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' 五
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Private Sub WorkingCalculator()
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Console.Title = "The Working Calculator| Learn X in Y Minutes"
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' 但是如果你希望有个能够处理加减乘除的计算器呢？
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' 只需将上面代码复制粘帖即可。
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Console.Write("First number: ") ' 输入第一个数
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Dim a As Double = Console.ReadLine
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Console.Write("Second number: ") ' 输入第二个数
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Dim b As Integer = Console.ReadLine
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Dim c As Integer = a + b
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Dim d As Integer = a * b
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Dim e As Integer = a - b
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Dim f As Integer = a / b
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' 通过以下代码我们可以将以上所算的加减乘除结果输出到屏幕上。
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Console.Write(a.ToString() + " + " + b.ToString())
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' 我们希望答案开头能有3个空格，可以使用String.PadLeft(3)方法。
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Console.WriteLine(" = " + c.ToString.PadLeft(3))
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Console.Write(a.ToString() + " * " + b.ToString())
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Console.WriteLine(" = " + d.ToString.PadLeft(3))
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Console.Write(a.ToString() + " - " + b.ToString())
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Console.WriteLine(" = " + e.ToString.PadLeft(3))
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Console.Write(a.ToString() + " / " + b.ToString())
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Console.WriteLine(" = " + e.ToString.PadLeft(3))
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Console.ReadLine()
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End Sub
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' 六
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Private Sub UsingDoWhileLoops()
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' 如同以上的代码一样
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' 这次我们将询问用户是否继续 （Yes or No?)
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' 我们将使用Do While循环，因为我们不知到用户是否需要使用一次以上。
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Console.Title = "UsingDoWhileLoops | Learn X in Y Minutes"
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Dim answer As String 'We use the variable "String" as the answer is text
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Do ' 循环开始
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Console.Write("First number: ")
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Dim a As Double = Console.ReadLine
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Console.Write("Second number: ")
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Dim b As Integer = Console.ReadLine
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Dim c As Integer = a + b
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Dim d As Integer = a * b
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Dim e As Integer = a - b
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Dim f As Integer = a / b
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Console.Write(a.ToString() + " + " + b.ToString())
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Console.WriteLine(" = " + c.ToString.PadLeft(3))
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Console.Write(a.ToString() + " * " + b.ToString())
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Console.WriteLine(" = " + d.ToString.PadLeft(3))
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Console.Write(a.ToString() + " - " + b.ToString())
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Console.WriteLine(" = " + e.ToString.PadLeft(3))
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Console.Write(a.ToString() + " / " + b.ToString())
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Console.WriteLine(" = " + e.ToString.PadLeft(3))
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Console.ReadLine()
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' 询问用户是否继续，注意大小写。
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Console.Write("Would you like to continue? (yes / no)")
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' 程序读入用户输入
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answer = Console.ReadLine() ' added a bracket here
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' 当用户输入"yes"时，程序将跳转到Do，并再次执行
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Loop While answer = "yes"
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End Sub
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' 七
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Private Sub UsingForLoops()
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' 有一些程序只需要运行一次。
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' 这个程序我们将实现从10倒数计数.
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Console.Title = "Using For Loops | Learn X in Y Minutes"
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' 声明变量和步长（即递减的速度，如-1，-2，-3等）。
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For i As Integer = 10 To 0 Step -1
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Console.WriteLine(i.ToString) ' 将计数结果输出的屏幕
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Next i ' 计算新的i值
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Console.WriteLine("Start")
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Console.ReadLine()
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End Sub
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' 八
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Private Sub ConditionalStatement()
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Console.Title = "Conditional Statements | Learn X in Y Minutes"
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Dim userName As String = Console.ReadLine
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Console.WriteLine("Hello, What is your name? ") ' 询问用户姓名
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userName = Console.ReadLine() ' 存储用户姓名
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If userName = "Adam" Then
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Console.WriteLine("Hello Adam")
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Console.WriteLine("Thanks for creating this useful site")
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Console.ReadLine()
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Else
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Console.WriteLine("Hello " + userName)
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Console.WriteLine("Have you checked out www.learnxinyminutes.com")
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Console.ReadLine() ' 程序停止，并输出以上文本
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End If
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End Sub
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' 九
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Private Sub IfElseStatement()
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Console.Title = "If / Else Statement | Learn X in Y Minutes"
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' 有时候我们需要考虑多于两种情况。
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' 这时我们就需要使用If条件语句。
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' If语句就好似个自动售货机，当用户输入A1，A2，A3，等去选择物品时，
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' 所有的选择可以合并到一个If语句中
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Dim selection As String = Console.ReadLine 'Value for selection
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Console.WriteLine("A1. for 7Up") ' A1 七喜
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Console.WriteLine("A2. for Fanta") ' A2 芬达
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Console.WriteLine("A3. for Dr. Pepper") ' A3 胡椒医生
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Console.WriteLine("A4. for Diet Coke") ' A4 无糖可乐
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Console.ReadLine()
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If selection = "A1" Then
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Console.WriteLine("7up")
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Console.ReadLine()
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ElseIf selection = "A2" Then
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Console.WriteLine("fanta")
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Console.ReadLine()
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ElseIf selection = "A3" Then
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Console.WriteLine("dr. pepper")
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Console.ReadLine()
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ElseIf selection = "A4" Then
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Console.WriteLine("diet coke")
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Console.ReadLine()
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Else
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Console.WriteLine("Please select a product") ' 请选择你需要的产品
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Console.ReadLine()
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End If
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End Sub
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End Module
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```
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## 参考
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我（译注：原作者）在命令行下学习的VB。命令行编程使我能够更好的了解程序编译运行机制，并使学习其它语言变得容易。
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如果希望进一步学习VB，这里还有更深层次的 <a href="http://www.vbbootcamp.co.uk/" Title="VB教学">VB教学（英文）</a>。
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所有代码均通过测试。只需复制粘帖到Visual Basic中，并按F5运行即可。
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