Streamreader

Question

我是 VB.NET 的新手，如果这是一个简单的问题，请原谅我。

我正在尝试使用 OpenFileFileDialog Box 将文本文件的内容读入多行文本框。我通过执行以下操作来做到这一点：

' Set Properties of OpenFileDialog
With OpenFileDialog1
    .FileName = ""
    .Title = "Open Text File"
    .InitialDirectory = "c:\"
    .Filter = "Text files|*.txt"
    .ShowDialog()
End With

' Populate Textbox with Selected Text File Contents
txtMain.Text = File.ReadAllText(OpenFileDialog1.FileName)

然后我想通读文件的每一行并检查前 3 个字符。如果前 3 个字符是 "LAX" 那么我知道文件的下一行应该以 "CHI"

开头

所以我想读取每一行，如果它以 "LAX" 开头，我想检查文件的下一行以确保前 3 个字符是 "CHI" 如果不是，我想从 "LAX" 行中删除任何换行符/回车符 returns，以便将下一行带到这一行的末尾。然后我想重复这个任务，直到下一行的前 3 个字符是 "CHI"

基本上这可以确保与 LAX 相关的所有内容都在同一行，因为目前这在文件中分为多行。

这是我目前所了解的，但我不知道下一步该怎么做。

Using streamReader As New StreamReader(OpenFileDialog1.FileName)

    While Not streamReader.EndOfStream
        Dim line As String = streamReader.ReadLine()
        If line.StartsWith("LAX") Then
            ' Go to end of this line and remove CR or LF. Then repeat the process for the next line down until the next line down starts with "CHI"
        End If
    End While
End Using

这有意义吗？

提前致谢。

Answer 1

与其像那样遍历行，不如找到 CHI 的索引并修复它之前的所有内容，然后获取它之后的所有内容。这有意义吗？

' sample text I made up from your description. correct it if it's wrong
Dim text =
$"LAX{Chr(10)}ABC
D{Chr(10)}EFGH{Chr(13)}I
JCHIKLMNOP
QRST
UVW
XY
Z"
' write it to a file
File.WriteAllText("file.txt", text)
' read it back, the rest of the code would be like yours
Dim textFromFile = File.ReadAllText("file.txt")
Dim indexOfChi = textFromFile.IndexOf("CHI")
Dim result = String.Concat(textFromFile.Take(indexOfChi))
' remove line feeds
result = String.Concat(result.Replace(Chr(10), String.Empty))
' remove carriage returns too (these can be done in one line with vbCrLf or Environment.NewLine)
result = String.Concat(result.Replace(Chr(13), String.Empty))
result &= Environment.NewLine & String.Concat(textFromFile.Skip(indexOfChi))
MessageBox.Show(result)

诚然，这不是最有效的代码，但它似乎有效。

Answer 2

我的输入（Test.txt 的内容）

something1
LAX something2
CHI something3
LAX something4
something5
something6
CHI something7
something8

我的输出（TextBox1 的内容）

something1
LAX something2
CHI something3
LAX something4 something5 something6
CHI something7
something8

代码

Dim line As String = ""
Using streamReader As New StreamReader(OpenFileDialog1.FileName)
     Dim previousLine As String = ""
     While Not streamReader.EndOfStream
         Dim nextLine = streamReader.ReadLine()
         If nextLine.StartsWith("LAX") Or nextLine.StartsWith("CHI") Then
             line &= Environment.NewLine & nextLine
             previousLine = nextLine
         ElseIf previousLine.StartsWith("LAX") Then
             line &= " " & nextLine
         Else
             ine &= Environment.NewLine & nextLine
         End If
     End While
End Using
TextBox1.Text = line

Streamreader - 阅读下一行

Streamreader - Read Next Line

vb.net

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