vba 编译错误：需要常量表达式
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Compile error: Constant expression required
提问by uncool
I've stumbled upon a compile error, but don't get what can be of the issue. When trying to chagne the symbol to an input variable ( TickerID ) I get the error, works perfectly fine otherwise when inputting e.g "yhoo" for the yahoo ticker name.
我偶然发现了一个编译错误，但不知道是什么问题。当尝试将符号更改为输入变量（ TickerID ）时，出现错误，否则在输入例如“yhoo”作为雅虎股票代码名称时工作正常。
Code
代码
Private Sub CmdBtn_Add_Click()
'---------------------------------------------------------------------------------------'
' Checks that inputted ticker name is correct and calls import class after confirmation
'---------------------------------------------------------------------------------------'
' General Variables---------'
Dim TickerID As String: TickerID = UCase(Add_Instrument.TxtBox_Instrument.Value)
'--------------------------'
'Check if input field is not empty
If TickerID = "" Or Application.WorksheetFunction.IsText(TickerID) = False Then
MsgBox "Please provide a valid ticker ID"
Exit Sub
End If
Debug.Print TickerID
'Check Ticker name exists through YQLBuilder class
Dim YQLBuilder As YQLBuilder: Set YQLBuilder = New YQLBuilder
Call YQLBuilder.TickerCheck(TickerID)
' Call ImportData(TickerID)
' MsgBox "Please check the ticker name. It is in the wrong format"
End Sub
Public Sub TickerCheck(TickerID As String)
'---------------------------------------------------------------------------------------'
' Built 2014-11-05 Allows parsing of XML data through YAHOO API YQL
' 2014-12-21: Not fully built yet, see where it can be of use
'---------------------------------------------------------------------------------------'
' General Variables---------'
Const ConnStringStart As String = "http://query.yahooapis.com/v1/public/yql?q="
Const ConnStringLast As String = "&diagnostics=true&env=store://datatables.org/alltableswithkeys"
'---------------------------'
Const ConnStringInput As String = "select * from yahoo.finance.stocks where symbol='" _
& TickerID & "'" **<----- Error here!**
Debug.Print ConnStringStart & ConnStringInput & ConnStringLast
Dim YQLNodes As MSXML2.IXMLDOMNodeList
Dim YQLReq As MSXML2.DOMDocument60
Set YQLReq = New MSXML2.DOMDocument60
YQLReq.async = False
YQLReq.Load ConnStringStart & ConnStringInput & ConnStringLast
YQLReq.setProperty "SelectionNamespaces", "xmlns:f='http://www.yahooapis.com/v1/base.rng'"
Set YQLNodes = YQLReq.SelectNodes("//CompanyName")
Dim xNode As MSXML2.IXMLDOMNode
For Each xNode In YQLNodes
Debug.Print xNode.Text
Next xNode
Debug.Print YQLNodes.Length
End Sub
回答by GolezTrol
The message is clear. When you declare a constant, the value you give it must be constant too. In this case, part of it is the parameter TickerId, which is variable. You cannot declare a constant with a variable value.
消息很明确。当你声明一个常量时，你给它的值也必须是常量。在这种情况下，它的一部分是参数 TickerId，它是可变的。您不能声明具有变量值的常量。
To solve this, I think you could just use Diminstead of Constand not make ConnStringInput a constant at all.
为了解决这个问题，我认为你可以只使用Dim而Const不是让 ConnStringInput 成为一个常量。
