如何删除vb.net中文本文件末尾的行？

问题描述

如何确保文件末尾没有多余的行？有点特别，我把一行分成三个地方，分别是17、90和120字节（总共：227字节）。我试图用Write替换WriteLine，那很好，但之后我不能写新行了！ 我当前的代码：

 Dim bibliotheque As New article

        With bibliotheque
            .Title = TextBox1.Text
            .Name = TextBox2.Text
            .Charge = TextBox3.Text
        End With

        Dim fileName As String = "c:\essai.librairie"

        Dim fs As FileStream = nothing
        Try
            fs = New FileStream(fileName,FileMode.Append)
            Using writer As StreamWriter = New StreamWriter(fs)

                writer.WriteLine(bibliotheque.Title.padright(17," "c).ToString & bibliotheque.Name.padright(90," "c).ToString & bibliotheque.Charge.padright(120," "c).ToString)

                ListBox1.Items.Add(bibliotheque.Name)

            End Using

        Finally
            If fs IsNot nothing Then
                fs.dispose()
            End If
        End Try

解决方法

您可以将 WriteLine 替换为 Write，使用布尔变量来了解您是否已经添加了第一行，如果已经添加了第一行，请使用以下命令添加回车/换行符一个带有空字符串的 WriteLine，在添加内容之前，如下所示：

    Dim linesExist As Boolean = IO.File.ReadAllLines(fileName).Count > 0
    Try
                fs = New FileStream(fileName,FileMode.Append)
                Using writer As StreamWriter = New StreamWriter(fs)
                    If linesExist Then writer.WriteLine()
                    writer.Write(bibliotheque.Title.PadRight(17," "c).ToString & bibliotheque.Name.PadRight(90," "c).ToString & bibliotheque.Charge.PadRight(120," "c).ToString)
                    ListBox1.Items.Add(bibliotheque.Name)
                End Using
    
            Finally
                If fs IsNot Nothing Then
                    fs.Dispose()
                End If
            End Try

显然，File.ReadAllLines 可能会很慢，您可以使用更优化的方法来检测文件是否存在以及是否有内容，但它确实解决了手头的问题。

,

Dim fileName As String = "c:\essai.librairie"
Dim bt As New article With {
            .Title = TextBox1.Text,.Name = TextBox2.Text,.Charge = TextBox3.Text
    }

Using fs As New FileStream(fileName,FileMode.Append)
Using writer As New StreamWriter(fs)
    If fs.Length > 0 Then writer.WriteLine()
    writer.Write($"{bt.Title,-17}{bt.Name,-90}{bt.Charge,-120}")
End Using
End Using
ListBox1.Items.Add(bt.Name)