Question

我试图创建一个读取大型文档的程序，例如圣经，并输出多个随机行。我可以让它输出一个随机线，但没有其他线。

最终目标是使用用户输入来确定显示的行数。

这是我的代码：

Public Class Form1
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        ' Dim howmanylines As Integer
        ' howmanylines = InputBox("how many lines for paragrpah", "xd",,,)
        'Dim count As Integer = 0
        ' Do Until count = howmanylines
        Dim sr As New System.IO.StreamReader("C:\Users\Dumpster Faggot\Desktop\bible.doc")
        Dim sr2 As New System.IO.StreamReader("C:\Users\Dumpster Faggot\Desktop\bible.doc")
        Dim sr3 As New System.IO.StreamReader("C:\Users\Dumpster Faggot\Desktop\bible.doc")
        Dim xd As Integer = 0
        Dim curline As Integer = 0
        Dim random As Integer = 0
        Do Until sr.EndOfStream = True
            sr.ReadLine()
            xd = xd + 1
        Loop
        sr.Dispose()
        sr.Close()
        Randomize()
        random = Rnd() * xd
        Do Until curline = random
            TextBox1.Text = sr2.ReadLine

            ' curline = curline + 1
            Randomize()
            random = Rnd() * xd

            TextBox1.Text = sr3.ReadLine

            curline = curline + 1

            '   count = count + 1
        Loop
    End Sub
End Class

Answer 1

我建议改进代码的一些事情。

实施Using。这将确保StreamReader在完成后处理掉。它可以节省您的记忆，减少代码行数，从而提高可读性。
我会考虑使用Integer.TryParse：

将数字的字符串表示形式转换为其等效的32位有符号整数。返回值表示转换是否成功。
您只需使用一个StreamReader并将所有行添加到List(Of String)。
使用StringBuilder添加您的行，然后将其输出到最后的TextBox。请注意，您必须导入System.Text才能引用StringBuilder类。
使用Random.Next：

返回指定范围内的随机整数。

最终结果将是这样的：

txtLines.Text = ""

Dim howManyLines As Integer = 0
If Integer.TryParse(txtUserInput.Text, howManyLines) Then

    Dim lines As New List(Of String)

    Using sr As New StreamReader("C:\test\test.txt")

        Do Until sr.EndOfStream()
            lines.Add(sr.ReadLine)
        Loop

    End Using

    Dim sb As New StringBuilder
    Dim rnd As New Random()

    For i = 0 To howManyLines - 1
        Dim nextLine As Integer = rnd.Next(lines.Count - 1)
        sb.AppendLine(lines(nextLine))
    Next

    txtLines.Text = sb.ToString()

End If

理想情况下，您可以将此代码放在按钮点击事件上。

输出从大文档到TextBox的随机行

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