vb.net 只接受文本框的数字
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Only accept digits for textbox
提问by Voldemort
I found this code for making my textbox only accept numbers.
我发现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
But... the user can't delete the numbers using the backspace button. How do I do then?
但是......用户无法使用退格按钮删除数字。那我怎么办？
采纳答案by Joel Coehoorn
You also need to handle pasted text (there may not be a keypress). The best way to do this is with a MaskedTextBox.
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。
回答by LV Ganesh
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
回答by Mousa Alfhaily
i develop your first code to allow the user to delete too.
我开发了您的第一个代码以允许用户也删除。
Here is the code :
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
I Hope My Code Was Useful To You :)
我希望我的代码对你有用:)
回答by djv
When I have had the requirement of an input which only accepts numbers, I have typically used the NumericUpDownclass. It handles limits and decimals too.
当我需要只接受数字的输入时，我通常使用NumericUpDown该类。它也处理限制和小数。
回答by KFC
Use this code, it will help you
使用此代码，它将帮助您
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
回答by Abdulaziz Alkuwari
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
回答by Phillip Olivier
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
回答by Allen
Here is some code that I wrote. It allows the user to delete, and the user can make the textbox blank if they desire. It handles when the user types a disallowed character, and it also handles when the user pastes text into the textbox. If the user pastes a string into the box that is a mix of valid and invalid characters, the valid characters will appear in the textbox, and the invalid characters will not.
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设为空白。它在用户键入不允许的字符时进行处理，并在用户将文本粘贴到文本框中时进行处理。如果用户将字符串粘贴到混合了有效和无效字符的框中，则有效字符将出现在文本框中，而无效字符则不会出现。
It also has logic in place to ensure that the cursor behaves normally. (A problem with setting the text to a new value is that the cursor is moved back to the beginning. This code tracks the original position, and makes adjustments to account for any invalid characters that are removed.)
它还具有确保光标正常运行的逻辑。（将文本设置为新值的一个问题是光标移回了开头。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。）
This code can be placed in the TextChaned event of any textbox. Be sure to change the name from TextBox1 to match your textbox.
此代码可以放置在任何文本框的 TextChaned 事件中。请务必将名称从 TextBox1 更改为与您的文本框匹配。
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
Note - if you have to do this for a bunch of textboxes, you can make a general purpose version of this by creating a sub that accepts a reference to a textbox as a parameter. Then you only need to call the sub from the TextChanged event.
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对文本框的引用作为参数的子来制作通用版本。然后你只需要从 TextChanged 事件中调用 sub。
