仅接受文本框的数字

Question

我找到了仅接受文本框的代码。

Private Sub TextBox1_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
    Dim allowedChars As String = "0123456789"
    If allowedChars.IndexOf(e.KeyChar) = -1 Then
        ' Invalid Character
        e.Handled = True
    End If
End Sub

但是...用户无法使用BackSpace按钮删除数字。那我该怎么办？

Answer 1

您还需要处理粘贴文本（可能没有按键）。最好的方法是与 maskedTextbox.

Answer 2

 Private Sub txtValue_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles                 txtValue.KeyPress
        'Dim allowedChars As String = "0123456789"
        'If allowedChars.IndexOf(e.KeyChar) = -1 Then
        '    ' Invalid Character
        '    e.Handled = True
        'End If
        'If (e.KeyChar = Microsoft.VisualBasic.Chr(8)) Then
        '    e.Handled = True
        'End If
        If Char.IsDigit(e.KeyChar) = False And Char.IsControl(e.KeyChar) = False Then
            e.Handled = True
        End If
    End Sub                                

Answer 3

伏地魔

我开发了您的第一个代码以允许用户删除。

这是代码：

Dim BACKSPACE As Boolean

Private Sub TextBox1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyDown
    If e.KeyCode = Keys.Back Then
        BACKSPACE = True
    Else
        BACKSPACE = False
    End If
End Sub

Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
    If BACKSPACE = False Then
        Dim allowedChars As String = "0123456789"
        If allowedChars.IndexOf(e.KeyChar) = -1 Then
            e.Handled = True
        End If
    End If
End Sub

我希望我的代码对您有用:)

Answer 4

使用此代码，它将为您提供帮助

Public Function OnlyDigitsOnKeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs)

Try

    If System.Char.IsDigit(e.KeyChar) = False And e.KeyChar <> Microsoft.VisualBasic.Chr(8)        And e.KeyChar <> Microsoft.VisualBasic.Chr(46) Or (InStr(sender.text, ".") > 0 And  e.KeyChar = Microsoft.VisualBasic.Chr(46)) 
    Then
                e.Handled = True
    End If
        Catch ex As Exception
            Common.ErrorHandler(ex)
        End Try
End Function

Answer 5

当我有只接受数字的输入的要求时，我通常使用 NumericUpDown 班级。它也处理限制和小数。

Answer 6

 Private Sub txtValue_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtValue.KeyPress
    Dim allowedChars As String = "."
    'If allowedChars.IndexOf(e.KeyChar) = -1 Then
    '    ' Invalid Character
    '    e.Handled = True
    'End If
    'If (e.KeyChar = Microsoft.VisualBasic.Chr(8)) Then
    '    e.Handled = True
    'End If
    If Char.IsDigit(e.KeyChar) = False And Char.IsControl(e.KeyChar) = False And allowedChars.IndexOf(e.KeyChar) = -1 Then
        e.Handled = True
    End If
End Sub

Answer 7

这是我写的一些代码。它允许用户删除，并且用户可以根据需要将文本框空白。当用户键入不允许的字符时，它会处理，并且当用户将文本粘贴到文本框中时，它也会处理。如果用户将字符串粘贴到框中，这些字符串是有效和无效字符的混合物，则有效字符将出现在文本框中，而无效的字符则不会。

它还具有适当的逻辑，以确保光标的行为正常。 （将文本设置为新值的问题是，光标已移至开始。此代码跟踪原始位置，并进行调整以说明被删除的任何无效字符。）

可以将此代码放置在任何文本框的文本chaned事件中。确保将名称从TextBox1更改为匹配您的文本框。

    Private Sub TextBox1_TextChanged(sender As System.Object, e As System.EventArgs) Handles TextBox1.TextChanged
    Dim selStart As Integer = TextBox1.SelectionStart
    Dim selMoveLeft As Integer = 0
    Dim newStr As String = "" 'Build a new string by copying each valid character from the existing string. The new string starts as blank and valid characters are added 1 at a time.

    For i As Integer = 0 To TextBox1.Text.Length - 1

        If "0123456789".IndexOf(TextBox1.Text(i)) <> -1 Then 'Characters that are in the allowed set will be added to the new string.
            newStr = newStr & TextBox1.Text(i)

        ElseIf i < selStart Then 'Characters that are not valid are removed - if these characters are before the cursor, we need to move the cursor left to account for their removal.
            selMoveLeft = selMoveLeft + 1

        End If
    Next

    TextBox1.Text = newStr 'Place the new text into the textbox.
    TextBox1.SelectionStart = selStart - selMoveLeft 'Move the cursor to the appropriate location.
End Sub

注意 - 如果您必须为一堆文本框执行此操作，则可以通过创建对文本框作为参数的引用来制作此的通用版本。然后，您只需要从文本变化事件中调用子。

Answer 8

Private Sub TMarksTextBox_KeyPress(sender As Object, e As KeyPressEventArgs) Handles TMarksTextBox.KeyPress
        If e.KeyChar < "0" OrElse e.KeyChar > "9" AndAlso e.KeyChar <> ControlChars.Back Then
            e.Handled = True
        End If
End Sub