Visual Basic问题获取列表框从文本文件填充

Question

我被卡住了，并试图多次重写我的代码，并找不到解决方案。该应用程序具有包含顺序访问文件中的项目和价格的文本文件。从列表框中选择应用时，应用程序应显示与该项目对应的价格。文本文件中的每一行都包含该项目的编号，后跟一个逗号，然后是价格。

我需要定义一个名为item的结构。该结构具有2个成员变量，一个用于存储项目号的字符串和一个用于存储价格的小数。我还需要用5个项目结构变量声明一个类级别的数组。负载甚至应该读取项目和价格，并将这些信息存储在类级数组中。然后它应该将项目号码添加到列表框中。

这是我迄今为止，但没有任何工作。

Option Explicit On 
Option Strict On 
Option Infer Off 

Public Class frmMain 
    'declare structure with 2 member variables 
    Structure Item 
     Public strItemNum As String 
     Public decPrice As Decimal 
    End Structure 

    'declare array for 5 item structure variables 
    Private items(4) As Item 

    Private Sub btnExit_Click(sender As Object, e As EventArgs) Handles btnExit.Click 
     Me.Close() 
    End Sub 

    Private Sub frmMain_Load(sender As Object, e As EventArgs) Handles Me.Load 
     'declare variables 
     Dim inFile As IO.StreamReader 
     Dim strLineofText As String 
     Dim intSub As Integer 

     'check if the file exists 
     If IO.File.Exists("ItemInfo.txt") Then 
      'open the file 
      inFile = IO.File.OpenText("ItemInfo.txt") 
      'read the file 
      Do Until inFile.Peek = -1 OrElse 
       intSub = items.Length 
       strLineofText = inFile.ReadLine.Trim 
       'add item to list box 
       lstNumbers.Items.Add(items(intSub).strItemNum) 
      Loop 
      'close the file 
      inFile.Close() 

     Else 
     MessageBox.Show("Can't find the ItemInfo.txtfile", 
         "Kensington Industries", 
         MessageBoxButtons.OK, 
         MessageBoxIcon.Information) 
     End If 
    End Sub 

    Private Sub lstNumbers_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstNumbers.SelectedIndexChanged 
     lblPrice.Text = items(lstNumbers.SelectedIndex).decPrice.ToString("C2") 
    End Sub 
End Class 

Answer 1

我认为你需要改变结构的名称。项目可以在另一个参考中使用。

尝试将名称更改为itemstr（例如）

 Do Until inFile.Peek = -1 OrElse 
     intSub = items.Length 
     strLineofText = inFile.ReadLine.Trim 
     'add item to list box 
     Dim arr As String() = str.Split(","C) 
     Dim valitem As New itemstr() 
     valitem.text = arr(0) 
     valitem.value = Convert.ToDecimal(arr(1)) 
     lstNumbers.Items.Add(valitem) 
    Loop 

Answer 2

谢谢大家。我最终重新开始，尝试一些不同的东西，终于有效了！

显式的选项在 选项严格在 选项推断关

公共类frmMain “声明结构 结构项目 公共strItemNum作为字符串 公共decPrice为十进制 末端结构

'declare class level array 
Public itemList(4) As Item 

Private Sub btnExit_Click(sender As Object, e As EventArgs) Handles btnExit.Click 
    Me.Close() 
End Sub 

Private Sub frmMain_Load(sender As Object, e As EventArgs) Handles Me.Load 
    'declare variables 
    Dim inFile As IO.StreamReader 
    Dim strLineOfText As String 
    Dim decPrice As Decimal 
    Dim strInfo(4, 1) As String 

    'check to see if the file exists 
    If IO.File.Exists("ItemInfo.txt") Then 
     'open the file 
     inFile = IO.File.OpenText("ItemInfo.txt") 

     For intRow As Integer = 0 To strInfo.GetUpperBound(0) 
      'read the line 
      strLineOfText = inFile.ReadLine 

      'assign substring from comma to first coloumn 
      strInfo(intRow, 0) = strLineOfText.Substring(0, strLineOfText.IndexOf(",")) 

      Dim intSep As Integer = strLineOfText.IndexOf(",") + 1 

      'assign substring after comma to 2nd column 
      strInfo(intRow, 1) = strLineOfText.Substring(intSep) 

      'assign first column value to strItemNum variable 
      itemList(intRow).strItemNum = (strInfo(intRow, 0)) 

      Decimal.TryParse(strInfo(intRow, 1), decPrice) 

      'assign 2nd columnn value to decPrice variable 
      itemList(intRow).decPrice = decPrice 


      'add item to listbox 
      lstNumbers.Items.Add(itemList(intRow).strItemNum) 
     Next intRow 

     'clost the file 
     inFile.Close() 

    Else 
     'error message if file cannot be found 
     MessageBox.Show("Can't find the ItemInfo.txtfile", 
         "Kensington Industries", 
         MessageBoxButtons.OK, 
         MessageBoxIcon.Information) 

    End If 
End Sub 

Private Sub lstNumbers_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Handles lstNumbers.SelectedIndexChanged 
    'display the price 
    lblPrice.Text = itemList(lstNumbers.SelectedIndex).decPrice.ToString("C2") 
End Sub 

结束