从传递的变量中读取文本文件

问：

我看过所有类似的问题，除非我遗漏了什么，否则它们不会回答我的问题;所以这里是：

我想在我的网页上打开一个文本文件;但标题是一个传递的变量。我在尝试使用变量时遇到错误。这是我的代码：

Option Explicit

Response.CodePage=65001
Response.CharSet="UTF-8"
DIM VTITLE

VTITLE = REQUEST("TITLE_")&".TXT"


Const Filename = VTITLE 'file to read in this case it is 101.txt
Const ForReading = 1, ForWriting = 2, ForAppending = 3
Const TristateUseDefault = -2, TristateTrue = -1, TristateFalse = 0

' Create a filesystem object
Dim FSO
set FSO = server.createObject("Scripting.FileSystemObject")

' Map the logical path to the physical system path
Dim Filepath
Filepath = Server.MapPath(Filename)

if FSO.FileExists(Filepath) Then

    ' Get a handle to the file
    Dim file    
    set file = FSO.GetFile(Filepath)

    ' Get some info about the file
    Dim FileSize
    FileSize = file.Size

    Response.Write "<p><b>File: " & Filename & " (size " & FileSize  &_
                   " bytes)</b></p><hr>"
    Response.Write "<pre>"

    ' Open the file
    Dim TextStream
    Set TextStream = file.OpenAsTextStream(ForReading, TristateUseDefault)

    ' Read the file line by line
    Do While Not TextStream.AtEndOfStream
        Dim Line
        Line = TextStream.readline
    
        ' Do something with "Line"
        Line = Line & vbCRLF
    
        Response.write Line 
    Loop


    Response.Write "</pre><hr>"

    Set TextStream = nothing
    
Else

    Response.Write "<h3><i><font color=red> File " & Filename &_
                       " does not exist</font></i></h3>"

End If

Set FSO = nothing

错误是.. 预期的文本常量

/_READING TEXTFILE.asp，第 8 行

const Filename = VTITLE '要读取
的文件 我尝试了不同的变量方法，例如 &VTITLE 等。

如果我将标题放在“”中，例如“101.txt”，则代码有效。 有人可以帮我解决这个问题吗？？我猜我不知道如何将变量变成常量。