将索引值传递给函数 [英] Passing an Index value to a Function

问题描述

根据主题，这就是我想要做的事情。



我在这里进行实验，所以我知道代码不完美&可能根本不工作，但我正在一点一点地工作，目前我只需要将Index值输入函数



我有一个循环如下......

 对于 Ix =  0    myArrayLen  -   1  
 如果 myXml1.Value.Chars（Ix）=   Y 然后 
 myWordData = GetNewsletterHeader（Ix）
 MsgBox（myWordData）
 结束 如果 
 下一步 

和一个函数如下......

 函数 GetNewsletterHeader（ ByRef  Ix  As   Int16 ） As   String  
  Dim  myXml2  As  XmlTextReader = 新 XmlTextReader（myDataFolder +   NewsLetter Items.xml）
 myItem =  项目 + Ix 
    while （myXml2.Read（））
  If  myXml2.IsStartElement（）< span class =code-keyword>然后 
 如果 myXml2.Name = myItem 那么 
 GetNewsletterHeader = myXml2.Value.ToString 
 结束 如果 
 结束 如果 
 循环 
 结束 功能 

它当前抛出异常从字符串转换项目到类型''Double''无效。，大概是因为Ix是指针而不是实际值。 div class =h2_lin>解决方案

1。删除 ByRef 并替换为 ByVal 。

函数GetNewsletterHeader（ByVal Ix As Int16）As String 

2.确保 Ix 在 For..Next 循环范围内声明为Int16



3.在函数GetNewsLetterHeader 中，添加以下行

将dim myItem作为字符串

4.将作业更改为 myItem 改为

 myItem =Item& Ix.ToString 

5.将以下行添加为包含此代码的Visual Studio文档文件的第一行

 Option Strict 

6.告诉我们哪一行会出错，哪些是Visual Studio Debugger显示错误中涉及的变量的值。

好的，异常措辞特别好，你不会遇到C＃的问题，但问题是与

 myItem =Item+ Ix 

你应该使用

 myItem =  项目 + Ix  .ToString  

你没有显示myItem的声明，但我认为它是这样的：

  Dim  myItem  as   Double  

由于编译错误正在谈论关于将字符串常量Item转换为double，以及为什么它不能这样做。由于Ix是Int16，myItem必须是双精度。

As per the Subject, that is what I want to do.

I am experimenting here, so I know the code is not perfect & may not even work at all, but I am working on it bit by bit and at the moment I just need to get the Index value into the Function

I have a Loop as follows ...

For Ix = 0 To myArrayLen - 1
    If myXml1.Value.Chars(Ix) = "Y" Then
        myWordData = GetNewsletterHeader(Ix)
        MsgBox(myWordData)
    End If
Next

and a Function as follows ...

Function GetNewsletterHeader(ByRef Ix As Int16) As String
    Dim myXml2 As XmlTextReader = New XmlTextReader(myDataFolder + "NewsLetter Items.xml")
    myItem = "Item" + Ix
    Do While (myXml2.Read())
        If myXml2.IsStartElement() Then
            If myXml2.Name = myItem Then
                GetNewsletterHeader = myXml2.Value.ToString
            End If
        End If
    Loop
End Function

It currently throws an exception "Conversion from string "Item" to type ''Double'' is not valid.", presumably because the Ix is a pointer rather than a real value.

解决方案

1. Remove the ByRef and replace with ByVal.

Function GetNewsletterHeader(ByVal Ix As Int16) As String

2. Ensure that Ix is declared as Int16 in the scope of the For..Next loop

3. In the Function GetNewsLetterHeader, add the following line

Dim myItem as string

4. Change the assignment to myItem to

myItem = "Item" & Ix.ToString

5. Add the following line as the very first line of the Visual Studio document file that contains this code

Option Strict

6. Let us know which line gets the error and what the Visual Studio Debugger displays for the values of the variables that are involved in the error.

Ok, the exception is particularly nicely worded and you wouldn''t get the problem with C# but the problem is with

myItem = "Item" + Ix

You should be using

myItem = "Item" + Ix.ToString

You don''t show your declaration of myItem, but I assume it is something like:

Dim myItem as Double

Since the compiler error is talking about converting a string constant "Item" to a double, and why it can''t do it. Since Ix is an Int16, myItem must be a double.

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