vb.net 只允许 2 个小数点

Allow only 2 Decimal points

提问by soclose

In window textbox, I'd like to just allow 2 decimal pointsonly. I could set text box only numeric but don't know how to limit 2 decimal points.

在窗口文本框中，我只想允许2 个小数点。我只能将文本框设置为数字，但不知道如何限制 2 个小数点。

For example, 743.56

例如，743.56

My code is below

我的代码在下面

  Private Sub txtPrice_KeyPress(sender As Object, e As KeyPressEventArgs) Handles txtPrice.KeyPress        
    'allow numeric 
    If Not Char.IsControl(e.KeyChar) AndAlso Not Char.IsDigit(e.KeyChar) AndAlso e.KeyChar <> "."c Then
        e.Handled = True
    End If

    ' only allow one decimal point
    If e.KeyChar = "."c AndAlso TryCast(sender, TextBox).Text.IndexOf("."c) > -1 Then
        e.Handled = True
    End If

   End Sub

How to?

如何？

回答by icktoofay

Try using a NumericUpDownrather than a TextBox. A NumericUpDownlets you specify the number of decimal places to go to, as well as automatically limiting it to numbers. You also have two handy little up and down buttons.

尝试使用 aNumericUpDown而不是 a TextBox。ANumericUpDown允许您指定要转到的小数位数，并自动将其限制为数字。您还有两个方便的上下按钮。

回答by ThatGuyInIT

A simpler solution would be to just use:

一个更简单的解决方案是使用：

txtPrice.Text = String.Format("{0:n2}", numberVariableHere);

回答by DareDevil

Here is the code, I have tested, I am just giving permission to user to enter only one digit after decimal point; you can change the value 2 to up to your choice.

这是代码，我已经测试过了，我只是允许用户只输入小数点后一位；您可以将值 2 更改为您的选择。

Private Sub tb_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles tb.KeyPress
    If Not Char.IsDigit(e.KeyChar) And Not e.KeyChar = "." Then
        e.Handled = True
    Else
        If e.KeyChar = "." And tb.Text.IndexOf(".") <> -1 Then
            e.Handled = True
        ElseIf e.KeyChar = "." Then
            e.Handled = False
        ElseIf Char.IsDigit(e.KeyChar) Then
            If tb.Text.IndexOf(".") <> -1 Then
                If tb.Text.Length >= tb.Text.IndexOf(".") + 2 Then  'replace 2 for greater numbers after decimal point
                    e.Handled = True
                End If
            End If
        End If
    End If
End Sub

I have tested this code for up-to 2,3,4 decimal points

我已经测试了最多 2,3,4 个小数点的代码

回答by Suji

i think this code help you to solve your problem

我认为这段代码可以帮助您解决问题

dim n as integer 
n=0
 Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
        If e.KeyChar = Chr(46) Then
            n = Len(TextBox1.Text)
        End If
        If Len(TextBox1.Text) >= n + 2 And n <> 0 Then
            TextBox1.Enabled = False
        End If
    End Sub

回答by Bulis

Private Sub txtVatRate_KeyPress(sender As Object, e As System.Windows.Forms.KeyPressEventArgs) Handles txtVatRate.KeyPress
    OnlyAllowPostiveNumbers(sender, e, 1)
End Sub

Public Function OnlyAllowPostiveNumbers(sender As Object, e As System.Windows.Forms.KeyPressEventArgs, Optional ByRef iDeimalPlaces As Integer = 0) As System.Windows.Forms.KeyPressEventArgs
    'Only allow numeric values with the exception of spaces ie '07969 860053' and backspace
    If (Microsoft.VisualBasic.Asc(e.KeyChar) < 48) Or (Microsoft.VisualBasic.Asc(e.KeyChar) > 57) Then
        e.Handled = True
    End If
    'Backspace
    If (Microsoft.VisualBasic.Asc(e.KeyChar) = 8) Then
        e.Handled = False
    End If
    If (Microsoft.VisualBasic.Asc(e.KeyChar) = 46) And InStr(sender.text, ".") < 1 Then
        e.Handled = False
    End If
    If (Microsoft.VisualBasic.Asc(e.KeyChar) > 48) And (Microsoft.VisualBasic.Asc(e.KeyChar) < 57) Then
        If InStr(sender.text, ".") > 0 Then
            Dim n As Integer = InStr(sender.text, ".")
            If n <= (sender.text.length - iDeimalPlaces) Then
                e.Handled = True
            End If
        End If
    End If
    Return e
End Function

回答by Anil Singh

Try this code (It will allow only numbers with a decimal point):

试试这个代码（它只允许带小数点的数字）：

Private Sub txtCostPrice_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtCostPrice.KeyPress
    If InStr(txtCostPrice.Text, ".") And e.KeyChar = "." Then e.Handled = True
    If Char.IsDigit(e.KeyChar) = False And Char.IsControl(e.KeyChar) = False Then
        If e.KeyChar <> "." Then e.Handled = True
    End If
End Sub

回答by soclose

Now it works. Please check my code below

现在它起作用了。请在下面检查我的代码

        '2 decimal points only
    'If key-in is after decimal point
    If txtPrice.SelectionStart > txtPrice.Text.IndexOf(Chr(46)) Then
        'If text not select All
        If txtPrice.SelectedText.Length = 0 Then
            If (txtPrice.Text.Trim() <> "") Then
                If (rexPrice.IsMatch(txtPrice.Text) = False) AndAlso e.KeyChar <> ControlChars.Back Then
                    e.Handled = True
                End If
            End If
        End If
    End If