如何确定是否在KeyPress事件中按下了Backspace? [英] How can I determine if the Backspace has been pressed in the KeyPress event?

问题描述

此:

http://msdn.microsoft.com/en-us /library/system.windows.forms.control.keypress.aspx

...表明我应该可以在KeyPress事件中访问e.KeyCode，但我似乎没有.我试图只允许1,2,3和退格键:

...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:

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; 
  }
}

...但是"e".不会像示例所示那样显示"KeyCode"值，并尝试使用Keys.Back来骂我，运算符'！='无法应用于类型为'char'和'System.Windows.Forms.Keys'的操作数"

...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'"

那我该怎么做呢?

推荐答案

尝试比较e.KeyChar != (char)Keys.Back，由于Keys是枚举，因此应将其强制转换为char

try comparing e.KeyChar != (char)Keys.Back, you should cast it to char since Keys is an enumeration

请参见: KeyPressEventArgs. KeyChar

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