这是一个高中班级的作业，我试了很多方法，查了很多资料，就是不明白!任务是创造一个神奇的词，无论用户想要它是什么。这很令人困惑，但我想学习!任何建议都会很棒!我已经尝试了下面的代码，但我不知道如何指定将其添加到标签的开始，分配是要有一个标签，并有按钮，能够在文本框中添加一个字符到标签的开始，中间和结束。这是周三10月20日的截止日期，所以如果你对visual basic有任何了解，我将非常感谢你的帮助。谢谢!
这是我尝试过的!它只向标签添加一次字符串字符，而不是再次添加，这是我试图添加到开头的唯一代码但还没有尝试添加到中间和结尾。
Dim MagicLetter As String
Dim NewString As String
Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
MagicLetter = TextBox1.Text
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
NewString = Len(Label2.Text)
NewString = Mid(MagicLetter, 1, 0)
NewString = MagicLetter.Insert(1, 0)
If MagicLetter = TextBox1.Text Then
NewString = Mid(MagicLetter, 1, 1)
End If
Label3.Text = "Magic Word: " & MagicLetter
NewString = MagicLetter & Label2.Text
问题在这里
NewString = Len(Label2.Text)
NewString = Mid(MagicLetter, 1, 0)
NewString = MagicLetter.Insert(1, 0)
你在这里所做的就是在同一个变量NewString中写入3次，所以最后只有最后一个值NewString = MagicLetter.Insert(1, 0)在变量中，因为之前的2被下一个覆盖了。因此，如果您删除前2行，这三行仍然执行相同的操作。
那么你就不需要任何全局变量了:
Dim MagicLetter As String
Dim NewString As String
可以在Button1_Click过程中使用局部变量。如果可以，总是使用局部变量而不是全局变量。
也不需要TextBox1_TextChanged事件，因为您对每个都不感兴趣。更改此文本框。当你点击按钮时，你只想知道它的内容。
所以我们可以在Button1_Click过程中做所有的事情
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim OriginalText As String
OriginalText = Label3.Text ' here we get the text from the label
Dim MagicLetter As String
MagicLetter = TextBox1.Text ' here we get the magic letter from the textbox
Dim NewText As String
NewText = OriginalText ' our new text should be created from the original text
' now we add the magic letter infront
NewText = MagicLetter & NewText
' now we add the magic letter in the end
NewText = NewText & MagicLetter
' now we add the magic letter in the middle
Dim TextLength As Long
TextLength = Len(NewText) ' here we get the length of our text (we need to split it in the middle)
Dim LeftPart As String
LeftPart = Mid(NewText, 1, CLng(TextLength / 2)) ' here we get the left part of the text
Dim RightPart As String
RightPart = Mid(NewText, Len(LeftPart) + 1) ' here we get the right part of the text
' now we add the magic letter between the left and right part
NewText = LeftPart & MagicLetter & RightPart
' finall we write the new text into our label
Label3.Text = NewText
End Sub
Public Class FormMagicWord
Private Function GenerateMagicWord(MagicLetter As Char, Type As String)
'Declare the MagicWord as the label, which is set as just "Magic" in the designer
Dim MagicWord As String = LblMagicWord.Text
'Use a case statement (which is just a cleaner if/else if/else)
Select Case Type
Case "Beginning"
'Combine the MagicLetter and the MagicWord into the MagicWord string.
MagicWord = MagicLetter & MagicWord
Case "Middle"
'Set the initial "midpoint" as 0 in-case the label is empty.
Dim MidPoint As Integer = 0
'Get the middle of the MagicWord string if its length > 0. I used Math.Floor() which will round down to the nearest whole number, so if the length was 9: 9/2 = 4.5 it would round down to 4.
'Alternatively you can use Math.Ceiling() which does the opposite, it rounds up to the next whole number, so if the length was 9: 9/2 = 4.5 it would round up to 5.
'It's cast as an integer (CInt) because we only care about whole numbers for this
If MagicWord.Length > 0 Then
MidPoint = CInt(Math.Floor(MagicWord.Length / 2))
End If
'Insert the MagicLetter at the midpoint of the MagicWord string.
MagicWord = MagicWord.Insert(MidPoint, MagicLetter)
Case "End"
'Combine the MagicWord and the MagicLetter into the MagicWord string.
MagicWord = MagicWord & MagicLetter
Case Else
'Not used, but this would be the "else" equivalent for a Select/Case/Switch statement
End Select
'Return the MagicWord string
Return MagicWord
End Function
'I've changed the handler to manage all three buttons: (BtnBeginning, BtnMiddle, BtnEnd) because the logic is the same for all of them.
'I've also changed the default sender object to Btn as a button, so it explicitly knows what type of control we're handling
Private Sub BtnBeginning_Click(Btn As Button, e As EventArgs) Handles BtnBeginning.Click, BtnMiddle.Click, BtnEnd.Click
'Get the magic letter as a single character, which is all we need.
'The designer also has the max length of the TxtMagicLetter textbox set to 1
Dim MagicLetter As Char = TxtMagicLetter.Text
'Call the GenerateMagicWord function passing the arguments of the letter and the text of the button (Beginning, Middle, End) which will run through the select statement to determine how to format the string
Dim MagicWord As String = GenerateMagicWord(MagicLetter, Btn.Text)
'Finally, set the MagicWord label as the returned string
LblMagicWord.Text = MagicWord
End Sub
End Class
这里也是设计器代码，这样你就可以复制/粘贴按钮/文本框/标签。
下面是如何访问设计背后的代码:Visual Studio 2010中的视图设计器代码<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Partial Class FormMagicWord
Inherits System.Windows.Forms.Form
'Form overrides dispose to clean up the component list.
<System.Diagnostics.DebuggerNonUserCode()> _
Protected Overrides Sub Dispose(ByVal disposing As Boolean)
Try
If disposing AndAlso components IsNot Nothing Then
components.Dispose()
End If
Finally
MyBase.Dispose(disposing)
End Try
End Sub
'Required by the Windows Form Designer
Private components As System.ComponentModel.IContainer
'NOTE: The following procedure is required by the Windows Form Designer
'It can be modified using the Windows Form Designer.
'Do not modify it using the code editor.
<System.Diagnostics.DebuggerStepThrough()> _
Private Sub InitializeComponent()
Me.TxtMagicLetter = New System.Windows.Forms.TextBox()
Me.BtnBeginning = New System.Windows.Forms.Button()
Me.BtnMiddle = New System.Windows.Forms.Button()
Me.BtnEnd = New System.Windows.Forms.Button()
Me.LbLMagicLetter = New System.Windows.Forms.Label()
Me.LblMagicWordLabel = New System.Windows.Forms.Label()
Me.LblMagicWord = New System.Windows.Forms.Label()
Me.SuspendLayout()
'
'TxtMagicLetter
'
Me.TxtMagicLetter.Location = New System.Drawing.Point(249, 12)
Me.TxtMagicLetter.MaxLength = 1
Me.TxtMagicLetter.Name = "TxtMagicLetter"
Me.TxtMagicLetter.Size = New System.Drawing.Size(246, 20)
Me.TxtMagicLetter.TabIndex = 0
'
'BtnBeginning
'
Me.BtnBeginning.Location = New System.Drawing.Point(12, 38)
Me.BtnBeginning.Name = "BtnBeginning"
Me.BtnBeginning.Size = New System.Drawing.Size(157, 33)
Me.BtnBeginning.TabIndex = 1
Me.BtnBeginning.Text = "Beginning"
Me.BtnBeginning.UseVisualStyleBackColor = True
'
'BtnMiddle
'
Me.BtnMiddle.Location = New System.Drawing.Point(175, 38)
Me.BtnMiddle.Name = "BtnMiddle"
Me.BtnMiddle.Size = New System.Drawing.Size(157, 33)
Me.BtnMiddle.TabIndex = 2
Me.BtnMiddle.Text = "Middle"
Me.BtnMiddle.UseVisualStyleBackColor = True
'
'BtnEnd
'
Me.BtnEnd.Location = New System.Drawing.Point(338, 38)
Me.BtnEnd.Name = "BtnEnd"
Me.BtnEnd.Size = New System.Drawing.Size(157, 33)
Me.BtnEnd.TabIndex = 3
Me.BtnEnd.Text = "End"
Me.BtnEnd.UseVisualStyleBackColor = True
'
'LbLMagicLetter
'
Me.LbLMagicLetter.AutoSize = True
Me.LbLMagicLetter.Location = New System.Drawing.Point(172, 12)
Me.LbLMagicLetter.Name = "LbLMagicLetter"
Me.LbLMagicLetter.Size = New System.Drawing.Size(66, 13)
Me.LbLMagicLetter.TabIndex = 4
Me.LbLMagicLetter.Text = "Magic Letter"
'
'LblMagicWordLabel
'
Me.LblMagicWordLabel.AutoSize = True
Me.LblMagicWordLabel.Font = New System.Drawing.Font("Microsoft Sans Serif", 14.25!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
Me.LblMagicWordLabel.Location = New System.Drawing.Point(8, 141)
Me.LblMagicWordLabel.Name = "LblMagicWordLabel"
Me.LblMagicWordLabel.Size = New System.Drawing.Size(112, 24)
Me.LblMagicWordLabel.TabIndex = 5
Me.LblMagicWordLabel.Text = "Magic Word"
'
'LblMagicWord
'
Me.LblMagicWord.AutoSize = True
Me.LblMagicWord.Font = New System.Drawing.Font("Microsoft Sans Serif", 14.25!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
Me.LblMagicWord.Location = New System.Drawing.Point(135, 141)
Me.LblMagicWord.Name = "LblMagicWord"
Me.LblMagicWord.Size = New System.Drawing.Size(0, 24)
Me.LblMagicWord.TabIndex = 6
Me.LblMagicWord.Text = "Magic"
'
'FormMagicWord
'
Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
Me.ClientSize = New System.Drawing.Size(800, 450)
Me.Controls.Add(Me.LblMagicWord)
Me.Controls.Add(Me.LblMagicWordLabel)
Me.Controls.Add(Me.LbLMagicLetter)
Me.Controls.Add(Me.BtnEnd)
Me.Controls.Add(Me.BtnMiddle)
Me.Controls.Add(Me.BtnBeginning)
Me.Controls.Add(Me.TxtMagicLetter)
Me.Name = "FormMagicWord"
Me.Text = "Magic Word"
Me.ResumeLayout(False)
Me.PerformLayout()
End Sub
Friend WithEvents TxtMagicLetter As TextBox
Friend WithEvents BtnBeginning As Button
Friend WithEvents BtnMiddle As Button
Friend WithEvents BtnEnd As Button
Friend WithEvents LbLMagicLetter As Label
Friend WithEvents LblMagicWordLabel As Label
Friend WithEvents LblMagicWord As Label
End Class
Dim magicWord As String = "abcdef"
Label1.Text = $"{TextBox1.Text}{String.Concat(magicWord.Take(magicWord.Length 2))}{TextBox1.Text}{String.Concat(magicWord.Skip(magicWord.Length 2))}{TextBox1.Text}"
当magicWord = "abcdefg"(奇数字符)，
插入的字符串并不完全在中间，但是在你的问题中要求不明确。
这不包括验证，如TextBox.Text应该是一个字符，魔术字长度是奇数或偶数。整除法用于向Take和Skip传递整数个字符。
这可能是不可用的，因为它不使用Mid或Len，但我张贴它为子孙后代
NewString = Len(Label2.Text)
你在这里有一个问题Len(String)返回一个整数，你已经声明NewString为String。
NewString = Mid(MagicLetter, 1, 0)
在下一行，丢掉NewString的值并赋值其他值。这有点傻，因为Mid(string, StartIndex, Length)因为长度是0，这让你得到一个空字符串。另一个让人困惑的地方是第二个参数，1。在。net中，索引从0开始，但这个"索引"从1开始。让我们抛弃旧的vb6方法，使用。net的改进。
NewString = MagicLetter.Insert(1, 0)
又是另一个赋值。NewString有点累了。关于。net中String的一个有趣之处在于它是不可变的(不能被改变)。在底层，每当字符串发生变化时，编译器就会抛出旧字符串，并创建一个全新的字符串。这一行的另一个问题是Insert的第二个参数接受String. 0不是String，它是一个Integer.
反斜杠表示整型除法
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
Dim MagicLetter As String = TextBox1.Text
Dim MagicWord = "antiestablishmentarianism"
Label1.Text = MagicWord & MagicLetter
Label2.Text = MagicLetter & MagicWord
Dim WordMiddle = MagicWord.Length 2
Label3.Text = MagicWord.Insert(WordMiddle, MagicLetter)
End Sub