每次按下键都会在文本框中自动保留小数位 VB.NET

Question

我在文本框中使用了按键事件。当我按下“2”时，我的期望值应该是 0.02。但是它显示“20.02”

我尝试的是将文本框属性“RighttoLeft”设置为是，以便在键入时从右开始。但是我希望我键入的 keychar 没有附加到我在代码中使用的 FactorDecimal 的输出中。

请看下面的代码。我基于来自其他 post:

的@Visual Vincent 评论

 Private Sub txtChequeAmt_KeyPress(sender As Object, e As KeyPressEventArgs) Handles txtChequeAmt.KeyPress
    If Char.IsDigit(e.KeyChar) = False Then
        e.Handled = True
    End If

    FactorDecimal1.AppendNumber(e.KeyChar)
    txtChequeAmt.Text = FactorDecimal1.ToString()

End Sub

    Public Class FactorDecimal
    Private value As String = "0"

    Public DecimalPlaces As Integer

    Public Sub AppendNumber(Character As Char)
        If Char.IsNumber(Character) = False Then
            Throw New ArgumentException("Input must be a valid numerical Character!", "Character")
            value = (value & Character).TrimStart("0"c)
        Else
            value = (value & Character).TrimStart("0"c)
        End If
    End Sub

    Public Sub RemoveRange(Index As Integer, Length As Integer)
        If value.Length >= Me.DecimalPlaces + 1 AndAlso Index + Length > value.Length - Me.DecimalPlaces Then
            Length -= 1 'Exclude decimal point
        End If

        If Index + Length >= value.Length Then
            Length = value.Length - Index 'Out of range
            value = value.Remove(Index, Length)
        End If

        If value.Length = 0 Then
            value = "0"
        End If
    End Sub

    Public Overrides Function ToString() As String
        Dim Result As Decimal

        If (Decimal.TryParse(value, Result)) = True Then
            Return (Result / (10 ^ Me.DecimalPlaces)).ToString("0." & New String("0"c, Me.DecimalPlaces))

        End If

        Return (Result / (10 ^ Me.DecimalPlaces)).ToString("0." & New String("0"c, Me.DecimalPlaces))
    End Function

    Public Sub New(DecimalPlaces As Integer)
        If DecimalPlaces <= 0 Then
            DecimalPlaces = 1
        End If
        Me.DecimalPlaces = DecimalPlaces
    End Sub
End Class

Answer 1

如果你想在文本框中使用你的计算，你需要设置 e.Handled = True。

Private Sub txtChequeAmt_KeyPress(sender As Object, e As KeyPressEventArgs) 
    If Char.IsDigit(e.KeyChar) = False Then
        e.Handled = True
        ' No point to continue if it is not a digit because 
        ' in that case you throw into the AppendNumber. Better avoid the exception
        Return
    End If

    FactorDecimal1.AppendNumber(e.KeyChar)
    txtChequeAmt.Text = FactorDecimal1.ToString()

    ' Don't let the forms engine add the number to your textbox 
    ' you have already defined its content 
    e.Handled = True
End Sub

每次按下键都会在文本框中自动保留小数位 VB.NET

EveryTime key is pressed will automatic decimal places in textbox VB.NET

vb.net

textbox

keypress