C# 如何确定 KeyPress 事件中是否按下了退格键？
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How can I determine if the Backspace has been pressed in the KeyPress event?
提问by B. Clay Shannon
This:
这个：
http://msdn.microsoft.com/en-us/library/system.windows.forms.control.keypress.aspx
http://msdn.microsoft.com/en-us/library/system.windows.forms.control.keypress.aspx
...indicates that I should have access to e.KeyCode in the KeyPress event, but I don't seem to. I'm trying to allow only 1,2,3, and backspace:
...表示我应该可以在 KeyPress 事件中访问 e.KeyCode，但我似乎没有。我试图只允许 1、2、3 和退格：
private void textBoxQH1_KeyPress(object sender, KeyPressEventArgs e) {
if ((e.KeyChar != '1') &&
(e.KeyChar != '2') &&
(e.KeyChar != '3') &&
(e.KeyChar != (Keys.Back))) {
e.Handled = true;
}
}
...but "e." does not show a "KeyCode" value like the example shows, and trying KeyChar with Keys.Back scolds me with, "Operator '!=' cannot be applied to operands of type 'char' and 'System.Windows.Forms.Keys'"
...但是“e” 没有像示例显示的那样显示“KeyCode”值，并且尝试使用 Keys.Back 的 KeyChar 责骂我，“Operator '!=' 不能应用于类型为 'char' 和 'System.Windows.Forms.Keys' 的操作数”
So how can I accomplish this?
那么我怎样才能做到这一点呢？
采纳答案by jorgehmv
try comparing e.KeyChar != (char)Keys.Back, you should cast it to char since Keys is an enumeration
尝试比较e.KeyChar != (char)Keys.Back，您应该将其转换为 char 因为 Keys 是一个枚举
see this: KeyPressEventArgs.KeyChar
回答by Neil Barnwell
I'm pretty sure I've only ever solved this by using the KeyDownevent instead; it has different event arguments.
我很确定我只是通过使用KeyDown事件来解决这个问题；它有不同的事件参数。
回答by ankur goel
Try to put a condition like this:
尝试设置这样的条件：
Code :
代码 ：
if (e.KeyCode == (Keys.Back))
{
if(textBox1.Text.Length >=3)
{
if (textBox1.Text.Contains("-"))
{
textBox1.Text.Replace("-", "");
}
}
}
