我已经为各种验证创建了一个可重用的文本框扩展类，并考虑共享它。

您所需要做的就是引发一个TextChange事件，然后调用Validate方法。它是这样的:

private void tbxAmount_TextChanged(object sender, EventArgs e)
{ 
    tbxAmount.Validate(TextValidator.ValidationType.Amount);
}

下面是扩展类:

public static class TextValidator
{
    public enum ValidationType
    {
        Amount,
        Integer
    }

    /// <summary>
    /// Validate a textbox on text change.
    /// </summary>
    /// <param name="tbx"></param>
    /// <param name="validationType"></param>
    public static void Validate(this TextBox tbx, ValidationType validationType)
    {
        PerformValidation(tbx, validationType);
        tbx.Select(tbx.Text.Length, 0);
    }


    private static void PerformValidation(this TextBox tbx, ValidationType validationType)
    {
        char[] enteredString = tbx.Text.ToCharArray();
        switch (validationType)
        {
            case ValidationType.Amount:
                tbx.Text = AmountValidation(enteredString);
                break;

            case ValidationType.Integer:
                tbx.Text = IntegerValidation(enteredString);
                break;

            default:
                break;
        }

        tbx.SelectionStart = tbx.Text.Length;
    }



    private static string AmountValidation(char[] enteredString)
    {
        string actualString = string.Empty;
        int count = 0;
        foreach (char c in enteredString.AsEnumerable())
        {
            if (count >= 1 && c == '.')
            { actualString.Replace(c, ' '); actualString.Trim(); }
            else
            {
                if (Char.IsDigit(c))
                {
                    actualString = actualString + c;
                }

                if (c == '.')
                {
                    actualString = actualString + c; count++;
                }

                else
                {
                    actualString.Replace(c, ' ');
                    actualString.Trim();
                }
            }
        }
        return actualString;
    }


    private static string IntegerValidation(char[] enteredString)
    {
        string actualString = string.Empty;
        foreach (char c in enteredString.AsEnumerable())
        {
            if (Char.IsDigit(c))
            {
                actualString = actualString + c;
            }
            else
            {
                actualString.Replace(c, ' ');
                actualString.Trim();
            }
        }
        return actualString;
    }
}

你可以在这里找到完整的代码

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。

简单的回答是:

_textBox.TextChanged += delegate(System.Object o, System.EventArgs e)
{
    TextBox _tbox = o as TextBox;
    _tbox.Text = new string(_tbox.Text.Where(c => (char.IsDigit(c)) || (c == '.')).ToArray());
};

这里有30多个答案，很多答案都是有用的。但我想分享system。windows。forms。textbox和system。windows。controls。textbox的通用形式。

在System.Windows.Controls.TextBox中没有可用的按键事件。 这个答案是为那些想用同样的逻辑实现System.Windows.Forms.TextBox和System.Windows.Controls.TextBox的人准备的。

这是NumberTextBox代码。对于System.Windows.Controls.TextBox，使用注释行代替之前的行。

public class NumberTextBox : System.Windows.Forms.TextBox
//public class NumberTextBox : System.Windows.Controls.TextBox
{
    private double _maxValue;
    private double _minValue;
    private bool _flag;
    private string _previousValue;

    public NumberTextBox()
    {
        this.TextAlign = HorizontalAlignment.Right;
        //TextAlignment = TextAlignment.Right;
        KeyDown += TextBox_KeyDown;
        TextChanged += TextBox_TextChanged;
        _minValue = double.MinValue;
        _maxValue = double.MaxValue;
    }

    private void TextBox_KeyDown(object sender, KeyEventArgs e)
    {
        _previousValue = this.Text;
        _flag = this.SelectedText.Length > 0;
    }

    private void TextBox_TextChanged(object sender, EventArgs e)
    //private void TextBox_TextChanged(object sender, TextChangedEventArgs e)
    {
        var text = this.Text;
        if (text.Length < 1) return;
        var cursorPosition = SelectionStart == 0 ? SelectionStart : SelectionStart - 1;
        var insertedChar = text[cursorPosition];
        if (IsInvalidInput(insertedChar, cursorPosition, text))
        {
            HandleText(text, cursorPosition);
        }
        ValidateRange(text, cursorPosition);
    }

    private bool IsInvalidInput(char insertedChar, int cursorPosition, string text)
    {
        return !char.IsDigit(insertedChar) && insertedChar != '.' && insertedChar != '-' ||
               insertedChar == '-' && cursorPosition != 0 ||
               text.Count(x => x == '.') > 1 ||
               text.Count(x => x == '-') > 1;
    }

    private void HandleText(string text, int cursorPosition)
    {
        this.Text = _flag ? _previousValue : text.Remove(cursorPosition, 1);
        this.SelectionStart = cursorPosition;
        this.SelectionLength = 0;
    }

    private void ValidateRange(string text, int cursorPosition)
    {
        try
        {
            if (text == "." || _minValue < 0 && text == "-") return;
            var doubleValue = Convert.ToDouble(text);
            if (doubleValue > _maxValue || doubleValue < _minValue)
            {
                HandleText(text, cursorPosition);
            }
        }
        catch (Exception)
        {
            HandleText(text, cursorPosition);
        }
    }

    protected void SetProperties(double minValue = double.MinValue, double maxValue = double.MaxValue)
    {
        _minValue = minValue;
        _maxValue = maxValue;
    }       

}

PositiveNumberTextBox代码:

public class PositiveNumberTextBox : NumberTextBox
{
    public PositiveNumberTextBox()
    {
        SetProperties(0);
    }
}

FractionNumberTextBox代码:

public class FractionNumberTextBox : NumberTextBox
{
    public FractionNumberTextBox()
    {
        SetProperties(0, 0.999999);
    }
}

我也在寻找最好的方法来检查文本框中只有数字和键盘的问题是，它不支持通过右键单击或剪贴板复制粘贴，所以提出了这个代码，验证光标离开文本字段时，它也检查空字段。(newguy改编版)

private void txtFirstValue_MouseLeave(object sender, EventArgs e)
{
    int num;
    bool isNum = int.TryParse(txtFirstValue.Text.Trim(), out num);

    if (!isNum && txtFirstValue.Text != String.Empty)
    {
        MessageBox.Show("The First Value You Entered Is Not a Number, Please Try Again", "Invalid Value Detected", MessageBoxButtons.OK, MessageBoxIcon.Error);
        txtFirstValue.Clear();
    }
}

我一直致力于一个组件的集合来完成WinForms中缺失的东西，这里是:高级表单

特别地，这是一个正则文本框类

/// <summary>Represents a Windows text box control that only allows input that matches a regular expression.</summary>
public class RegexTextBox : TextBox
{
    [NonSerialized]
    string lastText;

    /// <summary>A regular expression governing the input allowed in this text field.</summary>
    [Browsable(false), EditorBrowsable(EditorBrowsableState.Never)]
    [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
    public virtual Regex Regex { get; set; }

    /// <summary>A regular expression governing the input allowed in this text field.</summary>
    [DefaultValue(null)]
    [Category("Behavior")]
    [Description("Sets the regular expression governing the input allowed for this control.")]
    public virtual string RegexString {
        get {
            return Regex == null ? string.Empty : Regex.ToString();
        }
        set {
            if (string.IsNullOrEmpty(value))
                Regex = null;
            else
                Regex = new Regex(value);
        }
    }

    protected override void OnTextChanged(EventArgs e) {
        if (Regex != null && !Regex.IsMatch(Text)) {
            int pos = SelectionStart - Text.Length + (lastText ?? string.Empty).Length;
            Text = lastText;
            SelectionStart = Math.Max(0, pos);
        }

        lastText = Text;

        base.OnTextChanged(e);
    }
}

简单地添加像myNumbericTextBox这样的东西。RegexString = "^(\\d+|)$";应该足够了。