尝试一个MaskedTextBox。它采用一种简单的掩码格式，这样你就可以将输入限制为数字或日期之类的。

这可能有用。它允许“真实”数值，包括正确的小数点和前面的加号或减号。从相关的KeyPress事件中调用它。

       private bool IsOKForDecimalTextBox(char theCharacter, TextBox theTextBox)
    {
        // Only allow control characters, digits, plus and minus signs.
        // Only allow ONE plus sign.
        // Only allow ONE minus sign.
        // Only allow the plus or minus sign as the FIRST character.
        // Only allow ONE decimal point.
        // Do NOT allow decimal point or digits BEFORE any plus or minus sign.

        if (
            !char.IsControl(theCharacter)
            && !char.IsDigit(theCharacter)
            && (theCharacter != '.')
            && (theCharacter != '-')
            && (theCharacter != '+')
        )
        {
            // Then it is NOT a character we want allowed in the text box.
            return false;
        }



        // Only allow one decimal point.
        if (theCharacter == '.'
            && theTextBox.Text.IndexOf('.') > -1)
        {
            // Then there is already a decimal point in the text box.
            return false;
        }

        // Only allow one minus sign.
        if (theCharacter == '-'
            && theTextBox.Text.IndexOf('-') > -1)
        {
            // Then there is already a minus sign in the text box.
            return false;
        }

        // Only allow one plus sign.
        if (theCharacter == '+'
            && theTextBox.Text.IndexOf('+') > -1)
        {
            // Then there is already a plus sign in the text box.
            return false;
        }

        // Only allow one plus sign OR minus sign, but not both.
        if (
            (
                (theCharacter == '-')
                || (theCharacter == '+')
            )
            && 
            (
                (theTextBox.Text.IndexOf('-') > -1)
                ||
                (theTextBox.Text.IndexOf('+') > -1)
            )
            )
        {
            // Then the user is trying to enter a plus or minus sign and
            // there is ALREADY a plus or minus sign in the text box.
            return false;
        }

        // Only allow a minus or plus sign at the first character position.
        if (
            (
                (theCharacter == '-')
                || (theCharacter == '+')
            )
            && theTextBox.SelectionStart != 0
            )
        {
            // Then the user is trying to enter a minus or plus sign at some position 
            // OTHER than the first character position in the text box.
            return false;
        }

        // Only allow digits and decimal point AFTER any existing plus or minus sign
        if  (
                (
                    // Is digit or decimal point
                    char.IsDigit(theCharacter)
                    ||
                    (theCharacter == '.')
                )
                &&
                (
                    // A plus or minus sign EXISTS
                    (theTextBox.Text.IndexOf('-') > -1)
                    ||
                    (theTextBox.Text.IndexOf('+') > -1)
                )
                &&
                    // Attempting to put the character at the beginning of the field.
                    theTextBox.SelectionStart == 0
            )
        {
            // Then the user is trying to enter a digit or decimal point in front of a minus or plus sign.
            return false;
        }

        // Otherwise the character is perfectly fine for a decimal value and the character
        // may indeed be placed at the current insertion position.
        return true;
    }

你可以使用TextChanged/ Keypress事件，使用正则表达式过滤数字，并采取一些行动。

这是我的方法:

using linq (easy to modify filter) copy/paste proof code keeps caret position when you press a forbidden character accepts left zeroes and any size numbers private void numeroCuenta_TextChanged(object sender, EventArgs e) { string org = numeroCuenta.Text; string formated = string.Concat(org.Where(c => (c >= '0' && c <= '9'))); if (formated != org) { int s = numeroCuenta.SelectionStart; if (s > 0 && formated.Length > s && org[s - 1] != formated[s - 1]) s--; numeroCuenta.Text = formated; numeroCuenta.SelectionStart = s; } }

3解决方案

1)

//Add to the textbox's KeyPress event
//using Regex for number only textBox

private void txtBox_KeyPress(object sender, KeyPressEventArgs e)
{
if (!System.Text.RegularExpressions.Regex.IsMatch(e.KeyChar.ToString(), "\\d+"))
e.Handled = true;
}

2） 来自MSDN的另一个解决方案

// 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, 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;
        }
    }
}

}

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (nonNumberEntered == true)
    {
       MessageBox.Show("Please enter number only..."); 
       e.Handled = true;
    }
}

源http://msdn.microsoft.com/en-us/library/system.windows.forms.control.keypress (v =应用程序). aspx

3)使用MaskedTextBox: http://msdn.microsoft.com/en-us/library/system.windows.forms.maskedtextbox.aspx

这是一个简单的独立的Winforms自定义控件，从标准的TextBox派生而来，只允许System。Int32输入(它可以很容易地适用于其他类型，如System。Int64,等等)。它支持复制/粘贴操作和负数:

public class Int32TextBox : TextBox
{
    protected override void OnKeyPress(KeyPressEventArgs e)
    {
        base.OnKeyPress(e);

        NumberFormatInfo fi = CultureInfo.CurrentCulture.NumberFormat;

        string c = e.KeyChar.ToString();
        if (char.IsDigit(c, 0))
            return;

        if ((SelectionStart == 0) && (c.Equals(fi.NegativeSign)))
            return;

        // copy/paste
        if ((((int)e.KeyChar == 22) || ((int)e.KeyChar == 3))
            && ((ModifierKeys & Keys.Control) == Keys.Control))
            return;

        if (e.KeyChar == '\b')
            return;

        e.Handled = true;
    }

    protected override void WndProc(ref System.Windows.Forms.Message m)
    {
        const int WM_PASTE = 0x0302;
        if (m.Msg == WM_PASTE)
        {
            string text = Clipboard.GetText();
            if (string.IsNullOrEmpty(text))
                return;

            if ((text.IndexOf('+') >= 0) && (SelectionStart != 0))
                return;

            int i;
            if (!int.TryParse(text, out i)) // change this for other integer types
                return;

            if ((i < 0) && (SelectionStart != 0))
                return;
        }
        base.WndProc(ref m);
    }

2017年更新:我的第一个答案有一些问题:

你可以输入一个比给定类型的整数更长的值(例如2147483648大于Int32.MaxValue); 更一般地说，对于输入的结果没有真正的验证; 它只处理int32，你必须写特定的TextBox衍生控件为每种类型(Int64等)

所以我提出了另一个更通用的版本，它仍然支持复制/粘贴，+和-号等。

public class ValidatingTextBox : TextBox
{
    private string _validText;
    private int _selectionStart;
    private int _selectionEnd;
    private bool _dontProcessMessages;

    public event EventHandler<TextValidatingEventArgs> TextValidating;

    protected virtual void OnTextValidating(object sender, TextValidatingEventArgs e) => TextValidating?.Invoke(sender, e);

    protected override void WndProc(ref Message m)
    {
        base.WndProc(ref m);
        if (_dontProcessMessages)
            return;

        const int WM_KEYDOWN = 0x100;
        const int WM_ENTERIDLE = 0x121;
        const int VK_DELETE = 0x2e;

        bool delete = m.Msg == WM_KEYDOWN && (int)m.WParam == VK_DELETE;
        if ((m.Msg == WM_KEYDOWN && !delete) || m.Msg == WM_ENTERIDLE)
        {
            DontProcessMessage(() =>
            {
                _validText = Text;
                _selectionStart = SelectionStart;
                _selectionEnd = SelectionLength;
            });
        }

        const int WM_CHAR = 0x102;
        const int WM_PASTE = 0x302;
        if (m.Msg == WM_CHAR || m.Msg == WM_PASTE || delete)
        {
            string newText = null;
            DontProcessMessage(() =>
            {
                newText = Text;
            });

            var e = new TextValidatingEventArgs(newText);
            OnTextValidating(this, e);
            if (e.Cancel)
            {
                DontProcessMessage(() =>
                {
                    Text = _validText;
                    SelectionStart = _selectionStart;
                    SelectionLength = _selectionEnd;
                });
            }
        }
    }

    private void DontProcessMessage(Action action)
    {
        _dontProcessMessages = true;
        try
        {
            action();
        }
        finally
        {
            _dontProcessMessages = false;
        }
    }
}

public class TextValidatingEventArgs : CancelEventArgs
{
    public TextValidatingEventArgs(string newText) => NewText = newText;
    public string NewText { get; }
}

对于Int32，你可以从它导出，像这样:

public class Int32TextBox : ValidatingTextBox
{
    protected override void OnTextValidating(object sender, TextValidatingEventArgs e)
    {
        e.Cancel = !int.TryParse(e.NewText, out int i);
    }
}

或w/o派生，使用新的textvalididating事件，像这样:

var vtb = new ValidatingTextBox();
...
vtb.TextValidating += (sender, e) => e.Cancel = !int.TryParse(e.NewText, out int i);

但它的优点是它适用于任何字符串和任何验证例程。