如何使文本框只接受字母字符

3

我有一个Windows窗体应用程序,其中包含一个maskedtextbox控件,我希望该控件仅接受字母值。

理想情况下,按下除字母键以外的任何键都不会产生任何结果或立即向用户提供有关无效字符的反馈。

7个回答

6
这个问题可能已经在各种编程论坛上被问答了无数次。每个提供的答案都是针对特定要求的独特答案。
由于您正在使用MaskedTextBox,因此可以使用其他验证功能,而不需要处理按键。您只需将Mask属性设置为类似于“L”(需要字符)或“?”(可选字符)的内容即可。为了向用户显示输入不可接受的反馈,您可以使用BeepOnError属性或添加工具提示来显示错误消息。这种反馈机制应该在MaskedInputRejected事件处理程序中实现。
MaskedTextBox控件提供了ValidatingType属性来检查通过Mask要求的输入,但可能不是正确的数据类型。在此类型验证之后,会引发TypeValidationCompleted事件,您可以处理它以确定结果。
如果您仍然需要处理keypress事件,请继续阅读...!
在您的情况下,我推荐的方法是,不要处理KeyDown事件(您显然不需要高级按键处理能力)或使用Regex来匹配输入(坦率地说,这是过度杀手),而是简单地使用Char结构的内置属性。
private void maskedTextBox1_KeyPress(object sender, KeyPressEventArgs e)
{
  Char pressedKey = e.KeyChar;
  if (Char.IsLetter(pressedKey) || Char.IsSeparator(pressedKey) || Char.IsPunctuation(pressedKey))
  {
    // Allow input.
    e.Handled = false
  }
  else
    // Stop the character from being entered into the control since not a letter, nor punctuation, nor a space.
    e.Handled = true;
  }
}

请注意,这个代码片段可以让你处理标点和分隔符键。

4

来自MSDN(此代码演示如何处理KeyDown事件以检查输入的字符。在此示例中,它仅检查数字输入。您可以修改它,使其适用于字母输入而不是数字):

// 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;
    }
}

3
// This is  to allow only numbers.
// This Event Trigger, When key press event occures ,and it only allows the Number and Controls., 
private void txtEmpExp_KeyPress(object sender, KeyPressEventArgs e)
{
    if(Char.IsControl(e.KeyChar)!=true&&Char.IsNumber(e.KeyChar)==false)
    {
        e.Handled = true;
    }
}

//At key press event it will allows only the Characters and Controls.
private void txtEmpLocation_KeyPress(object sender, KeyPressEventArgs e)
{
    if (Char.IsControl(e.KeyChar) != true && Char.IsNumber(e.KeyChar) == true)
    {
        e.Handled = true;
    }
}

3

这段代码将区分字母字符按键和非字母字符按键:

private void maskedTextBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (Regex.IsMatch(e.KeyChar.ToString(), @"\p{L}"))
    {
        // this is a letter
    }
    else
    {
        // this is NOT a letter
    }
}

更新:请注意,上面的正则表达式模式仅匹配字母字符,因此不允许空格、逗号、点等。为了允许更多种类的字符,您需要将它们添加到模式中:

// allow alphabetic characters, dots, commas, semicolon, colon 
// and whitespace characters
if (Regex.IsMatch(e.KeyChar.ToString(), @"[\p{L}\.,;:\s]"))

1

//添加一个文本框,选择它并转到事件,在事件列表中双击“keypress”事件。

        if (!char.IsLetter(e.KeyChar))
        {
            MessageBox.Show("Enter only characters");
        }
    }

0

尝试this的代码

    private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
    {
        e.Handled = !(char.IsLetter(e.KeyChar) || e.KeyChar == (char)Keys.Back || e.KeyChar == (char)Keys.Space);
    }

0

这对我有效 :)

    private void txt_KeyPress(object sender, KeyPressEventArgs e)
    {
        e.Handled = !((e.KeyChar != 'ñ' && e.KeyChar != 'Ñ') && char.IsLetter(e.KeyChar));
    }

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