取消按键事件

我怎么能返回键？，意思是如果我只想在文本框中只允许整数值，我怎么能不允许用户不输入非整数，关于， KeyPress事件，我知道还有其他方法如表达式匹配字符串值，但我不想为文本框分配无效值。

 if (( value >0 a&&(value <=9)) then assigned else return 

Answer 1

使用Handled Property

 e.Handled = true; 

来自MSDN的示例： 链接

 // Boolean flag used to determine when a character other than a number is entered. private bool nonNumberEntered = false; // Handle the KeyDown event to determine the type of character entered into the control. private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e) { // Initialize the flag to false. nonNumberEntered = false; // Determine whether the keystroke is a number from the top of the keyboard. if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9) { // Determine whether the keystroke is a number from the keypad. if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9) { // Determine whether the keystroke is a backspace. if(e.KeyCode != Keys.Back) { // A non-numerical keystroke was pressed. // Set the flag to true and evaluate in KeyPress event. nonNumberEntered = true; } } } //If shift key was pressed, it's not a number. if (Control.ModifierKeys == Keys.Shift) { nonNumberEntered = true; } } // This event occurs after the KeyDown event and can be used to prevent // characters from entering the control. private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e) { // Check for the flag being set in the KeyDown event. if (nonNumberEntered == true) { // Stop the character from being entered into the control since it is non-numerical. e.Handled = true; } } 

Answer 2

创建一个字符串，其中包含允许用户输入的字符。

使用KeyDown或KeyUp处理特殊键

 private void tbN1_KeyPress(object sender, KeyPressEventArgs e) { String sKeys = "1234567890ABCDEF"; if (!sKeys.Contains(e.KeyChar.ToString().ToUpper())) e.Handled = true; } 

Answer 3

您可以使用如下的按键事件。 使用e.Handled为true取消用户输入

  private void textBox1_KeyPress(object sender, KeyPressEventArgs e) { if (!Char.IsDigit(e.KeyChar)) e.Handled = true; } 

Answer 4

从技术上讲，这是错误的，因为你标记了你的问题WPF。 但是，由于您接受了其他Windows窗体的答案，我将发布我的解决方案，该解决方案适用于实数而不是整数。 它也被本地化为仅接受当前语言环境的小数分隔符。

 private void doubleTextBox_KeyPress (object sender, KeyPressEventArgs e) { var textBox = sender as TextBoxBase; if (textBox == null) return; // did the user press their locale's decimal separator? if (e.KeyChar.ToString() == CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator) { if (textBox.Text.Length == 0) // if empty, prefix the decimal with a 0 { textBox.Text = "0" + CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator; e.Handled = true; textBox.SelectionStart = textBox.TextLength; } // ignore extra decimal separators else if (textBox.Text.Contains(CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator)) e.Handled = true; } // allow backspaces, but no other non-numeric characters; // note that arrow keys, delete, home, end, etc. do not trigger KeyPress else if (e.KeyChar != '\b' && (e.KeyChar < '0' || e.KeyChar > '9')) e.Handled = true; } 

Answer 5

对于WPF，使用PreviewTextInput事件，代码如下：

 // Filter out non-numeric keys. private void MyApp_PreviewTextInput(object sender, TextCompositionEventArgs e) { String sKeys = "1234567890"; if (!sKeys.Contains(e.Text)) e.Handled = true; } 

Answer 6

您可以使用MaskedTextBox并强制它仅为整数。

Answer 7

您可以从TextBoxinheritance，然后：

 Protected Overrides Sub OnTextInput(ByVal e As System.Windows.Input.TextCompositionEventArgs) Dim newChar As Char = Convert.ToChar(e.Text) If Not [Char].IsDigit(newChar) Then e.Handled = True End Sub 

C＃版本

 protected override void OnTextInput(System.Windows.Input.TextCompositionEventArgs e) {   char newChar = Convert.ToChar(e.Text);     if (!Char.IsDigit(newChar)) e.Handled = true; }