vb.net - 我的列表(字符串)被保存为 system.string (空)

Question

我正在尝试删除选定的行，然后将其余行保存到文件中。但是，当我保存它时，它完全清空了文件。

    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

看看代码中的这一行:

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”。您正在告诉流编写器将文本“System.String”写入文件。

要修复它，您需要类似这样的东西:

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