Question

我正在尝试删除所选行，然后将其余行保存到文件中。但是，当我保存它时，它会完全清空文件。

    Console.Write("Please eneter the first name of the student you wish to search for: ")
    searchfname = Console.ReadLine
    searchfname = StrConv(searchfname, VbStrConv.ProperCase)
    Console.Write("Please enter the second name of the student you wish to search for: ")
    searchsname = Console.ReadLine
    searchsname = StrConv(searchsname, VbStrConv.ProperCase)
    Dim foundItem() As String = Nothing
    Dim foundline As String = Nothing
    Dim fnsearch As String = String.Join(searchfname, searchsname)
    Dim lines As New List(Of String)(File.ReadAllLines("F:\Computing\Spelling Bee\stdnt&staffdtls.csv"))
    For Each line As String In lines
        If searchfname = item(3) And searchsname = item(4) Then
            Console.WriteLine(line)
            Console.WriteLine()
            Console.WriteLine("Are you sure you wish to delete this record? (y/n)")
        End If
        Dim answer As String
        answer = Console.ReadLine
        If answer = "y" Or answer = "Y" Then
            Console.Clear()
            lines.Remove(line)
            Using sw As New StreamWriter("F:\Computing\Spelling Bee\stdnt&staffdtls.csv")
                sw.WriteLine(lines.ToString)
            End Using
        ElseIf answer = "n" Or answer = "N" Then
            staffmenu()
        End If
    Next

Answer 1

方法List(Of T).ToString不会生成包含集合元素的值。相反，它只会返回类型名称。

您要查找的API是File.WriteAllLines。使用此代替StreamWriter和Using块

File.WriteAllLines("F:\Computing\Spelling Bee\stdnt&staffdtls.csv", lines)

Answer 2

在代码中查看此行：

sw.WriteLine(lines.ToString)

从该语句中提取lines.ToString表达式。该表达式的结果是“System.String”。您告诉流编写器将文本“System.String”写入文件。

要修复它，你需要更像这样的东西：

Using sw As New StreamWriter("F:\Computing\Spelling Bee\stdnt&staffdtls.csv")
    For Each line As String In lines
        sw.WriteLine(line)
    Next line
End Using

Answer 3

我可以看到这个问题可以从给定的答案和评论中解决，但我想在写入文件时添加一个使用Join函数的替代方法。尝试这样可能会有所帮助：

Using sw As New StreamWriter(.....)
   sw.WriteLine(Join(lines.ToArray(), Environment.NewLine))
End Using

由于使用VB.Net，这是一个vb.net特定的解决方案，不能在C＃中使用。对于C＃，请改用string.join。

希望它也有帮助！

我的列表（OF Strings）被保存为system.string（空）

3 个答案: