我在代码示例中损坏了字符串吗？ [英] Have I corrupted the string in the code example?

问题描述

大家好，



首先我在此示例中损坏了字符串值：

Hi All,

First off have I corrupted a string value in this example:

 Dim CommandB As String = ""
'do stuff not related 
' a lot of stuff not related
  Do Until RecString(ICount) = "EOF"
                ICount += 1
                If RecString(ICount) = "EOF" Then GoTo EndofCommandLoop  'Yes that's a Goto No I'm not responcible!
                CommandB(BCount) = RecString(ICount)
                BCount += 1
            Loop
EndofCommandLoop:
            'Take actions

啊，我吐在布偶上涂鸦（不写）这个烂摊子



VB里面无限智慧决定不编译这个，它返回

Ah, I spit on the muppet that doodled (not wrote) this mess

VB in it infinite wisdom has decided not to compile this, it returns

引用：

错误1属性'Chars'是'ReadOnly'。

Error 1 Property 'Chars' is 'ReadOnly'.

带有蓝色摇摆线，但是它编译了这个版本

with a blue wiggly line, however it compiles this version

 Dim CommandB As String
'do stuff not related 
' a lot of stuff not related
  Do Until RecString(ICount) = "EOF"
                ICount += 1
                If RecString(ICount) = "EOF" Then GoTo EndofCommandLoop
                CommandB(BCount) = RecString(ICount)
                BCount += 1
            Loop
EndofCommandLoop:
            'Take actions

使用CommandB（BCount）下的绿色小摆线作为以下内容

Works with a little green wiggly line under CommandB(BCount) as the following

Quote：

警告BC42104：变量'CommandB'在被赋值之前使用。在运行时可能会产生空引用异常。

warning BC42104: Variable 'CommandB' is used before it has been assigned a value. A null reference exception could result at runtime.

为什么，任何人都可以帮忙！

Why, can anyone help!

推荐答案

像这样使用StringBuilder类：

Use the StringBuilder class like this:

Dim sb As New System.Text.StringBuilder
'do stuff not related
' a lot of stuff not related
Do Until RecString(ICount) = "EOF"
    ICount += 1
    If RecString(ICount) = "EOF" Then GoTo EndofCommandLoop
    sb.Append(RecString(ICount))
    BCount += 1
Loop
EndofCommandLoop:
'Take actions
Dim CommandB As String = sb.ToString

好的，你可以通过这样做来修复第二个版本：

Okay, you can fix the second version by doing:

Dim CommandB As String = String.Empty

但是，看起来你只想在那里增加一个字符串，所以尝试将其更改为：

However, it looks like you are just tring to increment a string there so try changing it to this:

Dim CommandB As StringBuilder = New StringBuilder()
Do Until RectString(ICount) = EofCharacter
  ICount += 1
  If RecString(ICount) = EofCharacter Break
  CommandB.Append(RecString(ICount))

在您的示例中，您将字符与字符串进行比较EOF是一个字符串，因此您需要将EOF标记转换为字符。

In your example, you are comparing a character to a string "EOF" is a string, so you need to convert the EOF marker into a character.

这看起来像EOF字符上的一些变换形式的增量字符串拆分。

如果我错了，请忽略其余部分。

This looks like some perverted form of incremental string splitting on a EOF character.
If I am wrong please ignore the rest of this.

'*** assuming these are defined outside of the splitting method
   Const EOF As Char = Chr(26)

   Dim RecString As String = "sequence 1" & EOF & "sequence 2" & EOF & "sequence 3" & EOF
   Dim RecPosition As Int32 = 0 ' This was your ICount variable

'***

   ' the grunt work of find EOF marker and grabbing a substring
   Dim EOFposition As Int32
   Dim CommandB As String

   If RecPosition < RecString.Length Then
      EOFposition = RecString.IndexOf(value:=EOF, startIndex:=RecPosition)
      If EOFposition <> -1 Then
         If RecPosition = EOFposition Then
            CommandB = String.Empty
         Else
            CommandB = RecString.Substring(startIndex:=RecPosition, length:=(EOFposition - RecPosition))
         End If
      Else
         CommandB = RecString.Substring(startIndex:=RecPosition)
      End If
      RecPosition += CommandB.Length + 1 ' start of next sequence
   End If

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