Vb.net 我的列表（字符串）正在另存为system.string（空）

我正在尝试删除选定的行，然后将其余的保存到文件中。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

方法

List（Of T）.ToString

不生成包含集合元素的值。相反，它将只返回类型名

您正在查找的API是

File.writeAllines

。使用它而不是

StreamWriter

和

使用

块

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

---

请看代码中的这一行：

sw.WriteLine(lines.ToString)

从该语句中提取

行.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

    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

要解决此问题，您需要类似以下内容：

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

---

我可以从给出的答案和评论中看出这个问题可以得到解决，但我想添加一个替代方法，在文件中写入函数。这样做可能会有所帮助：

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

---

希望它也有帮助

您没有正确写入文件。改为使用File.writeAllines（）。您在这里以及前面的7个问题上得到了几个非常好的答案。当答案有帮助时，你应该开始接受答案。这与你的问题无关，但你是否在搜索JoeBlogs或Joe Blogs。。。。如果是后者，则更改您的联接，使其在searchfname和searchsname之间包含一个空格