如何将文本从文本框添加到数组并将其转换为双精度？

Question

我正在尝试为一个简单的计算器编写代码，该计算器将在一个数组中存储多达 10 个结果。

我的计算器部分工作正常，但在存储和显示数组结果时遇到问题。

Public Class wk2_David_Thieme_vb
Inherits System.Web.UI.Page

Dim resultArray(9) As Double
Dim i As Integer = 0

Protected Sub btnStore_Click(sender As Object, e As EventArgs) Handles btnStore.Click

    Dim Num As Double

    If i < 9 Then
        For i = 0 To resultArray.Length - 1
            Num = Convert.ToDouble(txtResult.Text)
            resultArray(i) = Num
            i += 1
        Next i
    Else
        txtResult.Text = "10 results already stored"
    End If

End Sub

Protected Sub btnDisplay_Click(sender As Object, e As EventArgs) Handles btnDisplay.Click
    For i = 0 To UBound(resultArray)
        lstResults.Items.Add(resultArray(i).ToString())
    Next
End Sub

无论用户如何输入计算器，结果都会在列表框中显示 10 个零。此外，一旦将 10 个条目添加到数组中，它就不会显示“已存储 10 个结果”。感谢您提供的任何帮助，我是 vb.net 的新手，还在学习中，所以请温柔。

Answer 1

我制作了使用 List (of T) 存储、显示和清除的示例：

Dim ListDoube As New List(Of Double)

Private Sub btnStore_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStore.Click
    Dim Num As Double = 0

    If ListDoube.Count < 10 Then
        ListDoube.Add(If(Double.TryParse(txtResult.Text, Num), Num, 0))
    Else
        txtResult.Text = "10 results already stored"
    End If
End Sub


Private Sub btnDisplay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisplay.Click
    For Each myVal In ListDoube
        lstResults.Items.Add(myVal.ToString)
    Next
End Sub

Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
    lstResults.Items.Clear()
End Sub

Answer 2

如果你还要使用数组：

Dim resultArray(9) As Double
Dim i As Integer = 0

Private Sub btnStore_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStore.Click
    Dim Num As Double = 0

    If i < 10 Then
        resultArray(i) = If(Double.TryParse(txtResult.Text, Num), Num, 0)
    Else
        txtResult.Text = "10 results already stored"

    End If
    i += 1
End Sub


Private Sub btnDisplay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisplay.Click
    For Each myVal In resultArray
        lstResults.Items.Add(myVal.ToString)
    Next
End Sub

Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
    For myCnt = 0 To 9
        resultArray(myCnt) = 0
    Next
    lstResults.Items.Clear()
    i = 0
    txtResult.Text = ""
End Sub

Answer 3

我想通了，主要是。现在唯一的问题是结果总是在列表的末尾有一个零......不知道如何解决它。因此，如果我输入 2 个条目，例如 4+2 = 6 & 2+2 = 4，那么结果数组中将包含 6、4、0。任何想法如何解决这一问题？再次感谢您的支持/帮助。

Public Shared resultArray(9) As Double
Public Shared i As Integer = 0

Protected Sub btnStore_Click(sender As Object, e As EventArgs) Handles btnStore.Click

    If i >= 9 Then
        lblError.Text = "10 results already stored"
    Else
        lblError.Text = ""
        resultArray(i) = Convert.ToDouble(txtResult.Text)
        If i < 9 Then
            i += 1
        End If
    End If

End Sub

Protected Sub btnDisplay_Click(sender As Object, e As EventArgs) Handles btnDisplay.Click

    If i <= 0 Then
        lblError.Text = "You must add numbers"
    Else
        lstResults.Items.Clear()
        lblError.Text = ""
        For Num = 0 To i
            lstResults.Items.Add(resultArray(Num))
        Next Num
    End If

End Sub

Answer 4

btnSave_Click 中不需要任何 For 循环。在您的情况下，for 循环的作用是遍历列表中的所有项目并将输入编号添加到您的数组中。相反，您需要将每个数字分别添加到数组中自己的位置。 为此，只需将 btnSave 更改如下：

Dim doubleArray(9) As Double
Dim i As Integer = 0

Private Sub btnSave_Click(sender As Object, e As EventArgs) Handles btnSave.Click
    Dim Num As Double

    If i < 10 Then
        doubleArray(i) = (If(Double.TryParse(txtResult.Text, Num), Num, 0))
        i += 1
    Else
        txtResult.Text = "10 results already stored"
    End If
End Sub

这样你的btnDisplay_Click里面就没有问题了。

您可以改为使用列表来保存结果。因此，您必须声明一个 List(Of Double) 而不是双数组。所以btnSave_Click应该改成如下：

Dim listOfDouble As New List(Of Double)

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim Num As Double

    If listOfDouble.Count < 10 Then
        listOfDouble.Add(If(Double.TryParse(txtResult.Text, Num), Num, 0))
    Else
        txtResult.Text = "10 results already stored"
    End If
End Sub

你可以使用 For Each 循环来迭代你的列表：

Private Sub btnDisplay_Click(sender As Object, e As EventArgs) Handles btnDisplay.Click
    For Each doubleVal In listOfDouble
        listResults.Items.Add(doubleVal)
    Next
End Sub