How do I prevent a keypress from updating a MaskedTextBox's text?
I need to validate characters entered by the user in a MaskedTextBox . Which characters are valid depends on those already entered. I've tried using IsInputChar and OnKeyPress , but whether I return false in IsInputChar or set e.Handled to true in OnKeyPress, the box's text is still set to the invalid value.
How do I prevent a keypress from updating a MaskedTextBox 's text?
UPDATE: MaskedTextBox not TextBox. I don't think that should make a difference, but from the number of people telling me that e.Handled should work, perhaps it does.
This will not type character 'x' in textbox1.
char mychar='x'; // your particular character
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == mychar)
e.Handled = true;
}
EDIT : It works for MaskedTextBox as well.
HTH
The KeyPress should do it; are you doing this at the form? or at the control? For example:
static void Main() {
TextBox tb = new TextBox();
tb.KeyPress += (s, a) =>
{
string txt = tb.Text;
if (char.IsLetterOrDigit(a.KeyChar)
&& txt.Length > 0 &&
a.KeyChar <= txt[txt.Length-1])
{
a.Handled = true;
}
};
Form form = new Form();
form.Controls.Add(tb);
Application.Run(form);
}
(only allows "ascending" characters)
Note that this won't protect you from copy/paste - you might have to look at TextChanged and/or Validate as well.
http://msdn.microsoft.com/en-us/library/system.windows.forms.control.keydown.aspx可能帮助，KeyDown事件？
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