Question

我正在尝试制作一个程序来检查所有产品的库存文件，并使用输入的GTIN代码中的正确信息返回（您将（希望）通过查看我的代码了解）

Public Class Form1
    Dim FILE_NAME As String = "H:\Visual Studio 2013\Projects\Control Task 2 Barcode Orders\Control Task 2 Barcode Orders\bin\Debug\receipt_orders.txt"
    Dim GTIN As String
    Dim LineContaining As String
    Dim quantity As Integer
    Dim description As String
    Dim singleamount As String
    Dim singleprice As Double
    Dim totalprices As Double
    Private Sub btnEnterGTIN_Click(sender As Object, e As EventArgs) Handles btnEnterGTIN.Click
        GTIN = getValidGTIN()
        Call itemfinder(GTIN)
    End Sub
    Function getValidGTIN()
        Dim GTIN, ValidGTINAmountCharacters As String
        Dim GTINOK As Boolean
        'Declaring variables.
        GTINOK = False
        Do
            GTIN = InputBox("Enter the full GTIN Number (it should be 8 digits long)")
            'Prompts the user to enter the GTIN.
            ValidGTINAmountCharacters = Len(GTIN)
            'Makes it so that the amount of characters of the GTIN is stored in the variable ValidGTINAmountCharacters.
            If ValidGTINAmountCharacters = 8 Then GTINOK = True
            'Makes it so the program will only accept an input if it was 8 characters long.
            If Not IsNumeric(GTIN) Then GTINOK = False
            'Makes it so that if any other character typed in apart from a number is not valid.
            If Not GTINOK Then MsgBox("The GTIN Number isn't valid. It should be a 8 digit number. (Should not contain letters or symbols).")
            'Makes it so that if the GTIN is not valid according to the above, a message appears saying it is invalid.
        Loop Until GTINOK
        Return GTIN
    End Function
    Private Sub itemfinder(ByVal GTIN As String)
        Using reader As New IO.StreamReader("receipt_orders.txt")
            While Not reader.EndOfStream
                Dim line As String = reader.ReadLine()
                If line.Contains(GTIN) Then
                    line = LineContaining
                    Exit While
                End If
            End While
        End Using
        description = Mid$(LineContaining, 10, 17)
        singleamount = Mid$(LineContaining, 38, 4)
        quantity = InputBox("Enter the amount required")
        totalprices = quantity * singleamount
        lstGTIN.Items.Add(GTIN)
        lstName.Items.Add(description)
        lstQuantity.Items.Add(quantity)
        lstSinglePrice.Items.Add(singleamount)
        lstTotal.Items.Add(totalprices)

        Dim sum As Double
        For x As Integer = 0 To lstTotal.Items.Count - 1

            sum += Val(lstTotal.Items.Item(x).ToString)
        Next
        txtTotalPrice.Text = sum.ToString
    End Sub
End Class

当我输入数量和物品代码时，我得到一个与总价格计算有关的错误代码 - 我不知道如何解决这个问题！此外，我使用的文本文件看起来像这样

12345670 L-Shaped Brackets           7.20
10101010 Television                  1.80
69696969 Screws                      0.20

请尽量解释如何解决这个问题！我不是很熟悉Visual Basic！

Answer 1

其中的一些代码，例如使用Call关键字，表示vb6 / vbscript时代的思维方式。这是使用现代和更清晰的VB.Net编码样式的相同功能的实现：

Public Class ProductItem
    Public Property GTIN As Integer
    Public Property Description As String
    Public Property ItemPrice As Decimal

    Protected Property SourceData As String

    Public Shared Function FromLineString(ByVal lineString As String) As OrderLine
        Return New ProductItem() With
        {
            .Description = lineString.SubString(9,17),
            .ItemPrice = Decimal.Parse(lineString.SubString(37,4)),
            .GTIN = Int32.Parse(lineString.SubString(0,8)), 'Guessed at this field
            .SourceData = lineString    
        }
    End Function
End Class

Public Class Form1
    Const FILE_NAME As String = "H:\Visual Studio 2013\Projects\Control Task 2 Barcode Orders\Control Task 2 Barcode Orders\bin\Debug\receipt_orders.txt"

    Private Sub btnEnterGTIN_Click(sender As Object, e As EventArgs) Handles btnEnterGTIN.Click
        Dim item As ProductItem = itemfinder(Form1.InputValidGTIN())
        If item Is Nothing Then Exit Sub ' May want to show error here

        Dim QTY As Integer =  Form1.InputInteger("Enter the amount required", "Input was not a valid Integer. Please try again.")

        Me.SuspendLayout()
        lstGTIN.Items.Add(item.GTIN)
        lstName.Items.Add(item.Description)
        lstQuantity.Items.Add(QTY)
        lstSinglePrice.Items.Add(item.ItemPrice)
        lstTotal.Items.Add(QTY * item.ItemPrice)

        txtTotalPrice.Text = lstTotal.Items.Cast(Of Decimal).Sum().ToString()
        Me.ResumeLayout()
    End Sub

    Public Shared Function InputValidGTIN() As String
        Dim GTIN As String = InputBox("Enter the full GTIN Number (it should be 8 digits long)").Trim()

        While Not IsValidGTIN(GTIN)
            MsgBox("The GTIN Number isn't valid. It should be a 8 digit number. (Should not contain letters or symbols).")
            GTIN = InputBox("Enter the full GTIN Number (it should be 8 digits long)").Trim()
        End While

        Return GTIN
    End Function

    Public Shared Function IsValidGTIN(ByVal GTIN As String) As Boolean
        Static regex As New Regex("^\d{8}$")
        Return regex.IsMatch(GTIN)
    End Function

    Public Shared Function InputInteger(ByVal PromptText As String, ByVal RePromptText As String) As Integer
        Dim result As Integer
        Dim input As String = InputBox(PromptText)

        While Not Int32.TryParse(input, result)
             input = InputBox(RePromptText)
        End While

        Return result
    End Function

    Private Function itemfinder(ByVal GTIN As String) As ProductItem
        Using reader As New IO.StreamReader(FILE_NAME)
            Dim line As String = reader.ReadLine()
            While line IsNot Nothing

                If line.Contains(GTIN) Then
                    Return ProductItem.FromLineString(line)
                End If
                line = reader.ReadLine()
            End While
        End Using
        Return Nothing
    End Function
End Class

从文本文件中获取字符串（Visual Basic）

1 个答案: