使用VB.net动态编辑CSV文件的内容(Dynamically edit Contents of a CSV file using VB.net)

我有这个代码

Dim fileReader As System.IO.StreamReader fileReader = My.Computer.FileSystem.OpenTextFileReader("Filepath") Dim stringReader As String 'read csv file from first to last line While fileReader.ReadLine <> "" 'get data of line stringReader = fileReader.ReadLine() 'check the number of commas in the line Dim meh As String() = stringReader.Split(",") If meh.Length > 14 Then My.Computer.FileSystem.WriteAllText("Filepath", "asd", True) ElseIf meh.Length < 14 Then My.Computer.FileSystem.WriteAllText("Filepath", "asd", True) ElseIf meh.Length = 14 Then MsgBox("This line of the file has " & stringReader & meh.Length & "commas") End If End While End End Sub

为了解释，上面的代码将检查CSV文件的每一行以检查天气内容有14个逗号（'）。然后，如果该行有更多逗号，代码将减少到14，如果没有，它将写入逗号，使其等于14.上述条件尚未创建，因此代码仅用于测试。我读了一些关于WriteAllText的内容，这段代码给了我错误：

The process cannot access the file 'filepath' because it is being used by another process.

我认为，这意味着我无法编辑CSV文件，因为我目前正在使用其数据。

我的问题是，即使我检查其内容，我怎么能编辑CSV文件的内容？

请忽略此代码

My.Computer.FileSystem.WriteAllText("Filepath", "asd", True)

因为我使用这段代码只是为了测试，如果我能设法将它写入CSV文件。

我感谢你的帮助。

I have this code

Dim fileReader As System.IO.StreamReader fileReader = My.Computer.FileSystem.OpenTextFileReader("Filepath") Dim stringReader As String 'read csv file from first to last line While fileReader.ReadLine <> "" 'get data of line stringReader = fileReader.ReadLine() 'check the number of commas in the line Dim meh As String() = stringReader.Split(",") If meh.Length > 14 Then My.Computer.FileSystem.WriteAllText("Filepath", "asd", True) ElseIf meh.Length < 14 Then My.Computer.FileSystem.WriteAllText("Filepath", "asd", True) ElseIf meh.Length = 14 Then MsgBox("This line of the file has " & stringReader & meh.Length & "commas") End If End While End End Sub

To explain, the above code would check EACH line of a CSV file to check weather the contents has 14 commas('). Then if that line has more commas, the code will reduce it to 14, and if not, it would write commas so that it would be equal to 14. The above conditions are not created yet, so the code is just for testing. I read something about WriteAllText and this code gives me the error :

The process cannot access the file 'filepath' because it is being used by another process.

Which, I think, means that I cant edit the CSV file because I'm currently using its data.

My question is, how could I edit the contents of the CSV file even when I am checking its contents?

Please do disregard this code

My.Computer.FileSystem.WriteAllText("Filepath", "asd", True)

as I use this code just for testing, if ever I could manage to write it to the CSV file.

I Thank you for all your help.

最满意答案

如果您的CSV不是太大，您可以在内存中阅读它并使用它。完成后，您可以在磁盘上再次写入。

'Declare 2 List (or you can work directly with one) Dim ListLines As New List(Of String) Dim ListLinesNEW As New List(Of String) 'Read the file Using MyCSVread As New IO.FileStream("C:\MyCSV.csv", IO.FileMode.Open, IO.FileAccess.ReadWrite) 'Read all the lines and put it in a list of T (string) Using sReader As IO.StreamReader = New IO.StreamReader(MyCSVread) Do While sReader.Peek >= 0 ListLines.Add(sReader.ReadLine) Loop End Using End Using 'Your code for work with the line. Here you can write the new lines in the NEW list of string or work directly in the first For L As Integer = 0 To ListLines.Count - 1 Dim meh As String() = ListLines(L).Split(",") If meh.Length > 14 Then 'your code ... ElseIf meh.Length < 14 Then 'your code ... ElseIf meh.Length = 14 Then MessageBox.Show("The line " & (ListLines(L) + 1) & " of the file has " & meh.Length & "commas", "MyApp", MessageBoxButtons.OK, MessageBoxIcon.Exclamation) End If Next 'Open again the file for write Using MyCSVwrite As New IO.FileStream("C:\MyCSV.csv", IO.FileMode.Open, IO.FileAccess.ReadWrite) 'Write back the file with the new lines Using sWriter As IO.StreamWriter = New IO.StreamWriter(MyCSVwrite) For Each sLine In ListLinesNEW.ToArray sWriter.WriteLine(sLine) Next End Using End Using

“使用”自动关闭文件流或流读取器/写入或您使用的内容。那么你就不会有“已经在使用的文件”这样的问题。

希望这有帮助。

If your CSV is not too big, you can read it in memory and work with it. When you have finish you can write it again on disk.

'Declare 2 List (or you can work directly with one) Dim ListLines As New List(Of String) Dim ListLinesNEW As New List(Of String) 'Read the file Using MyCSVread As New IO.FileStream("C:\MyCSV.csv", IO.FileMode.Open, IO.FileAccess.ReadWrite) 'Read all the lines and put it in a list of T (string) Using sReader As IO.StreamReader = New IO.StreamReader(MyCSVread) Do While sReader.Peek >= 0 ListLines.Add(sReader.ReadLine) Loop End Using End Using 'Your code for work with the line. Here you can write the new lines in the NEW list of string or work directly in the first For L As Integer = 0 To ListLines.Count - 1 Dim meh As String() = ListLines(L).Split(",") If meh.Length > 14 Then 'your code ... ElseIf meh.Length < 14 Then 'your code ... ElseIf meh.Length = 14 Then MessageBox.Show("The line " & (ListLines(L) + 1) & " of the file has " & meh.Length & "commas", "MyApp", MessageBoxButtons.OK, MessageBoxIcon.Exclamation) End If Next 'Open again the file for write Using MyCSVwrite As New IO.FileStream("C:\MyCSV.csv", IO.FileMode.Open, IO.FileAccess.ReadWrite) 'Write back the file with the new lines Using sWriter As IO.StreamWriter = New IO.StreamWriter(MyCSVwrite) For Each sLine In ListLinesNEW.ToArray sWriter.WriteLine(sLine) Next End Using End Using

The "Using" auto close the filestream or a streamreader/write or what you use. Then you will not have problem like "file already in use".

Hope this help.

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