文本框仅接受数字

Question

我找到了这段代码，使我的文本框只接受数字。

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......用户无法使用退格按钮删除数字。那我该怎么办呢？

Answer 1

 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 2

您还需要处理粘贴的文本（可能没有按键）。最好的方法是使用 MaskedTextBox。

Answer 3

voldemort

我开发了您的第一个代码以允许用户也删除。

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，它将对您有所帮助

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

当我需要只接受数字的输入时，我通常使用 NumericUpDown 类。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留空。它会处理用户键入不允许的字符的情况，也会处理用户将文本粘贴到文本框中的情况。如果用户将包含有效字符和无效字符的字符串粘贴到文本框中，则有效字符将出现在文本框中，而无效字符则不会出现。

它还具有适当的逻辑来确保光标正常运行。 （将文本设置为新值的一个问题是光标移回到开头。此代码跟踪原始位置，并进行调整以考虑删除的任何无效字符。）

此代码可以放置在任何文本框的 TextChaned 事件。请务必更改 TextBox1 的名称以匹配您的文本框。

    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 - 如果您必须对一堆文本框执行此操作，您可以通过创建一个接受文本框引用作为参数的子程序来制作通用版本。然后你只需要从 TextChanged 事件中调用 sub 即可。

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