这个功能包括复制粘贴，拖放，按下键，防止溢出，非常简单

public partial class IntegerBox : TextBox 
{
    public IntegerBox()
    {
        InitializeComponent();
        this.Text = 0.ToString();
    }

    protected override void OnPaint(PaintEventArgs pe)
    {
        base.OnPaint(pe);
    }

    private String originalValue = 0.ToString();

    private void Integerbox_KeyPress(object sender, KeyPressEventArgs e)
    {
        originalValue = this.Text;
    }

    private void Integerbox_TextChanged(object sender, EventArgs e)
    {
        try
        {
            if(String.IsNullOrWhiteSpace(this.Text))
            {
                this.Text = 0.ToString();
            }
            this.Text = Convert.ToInt64(this.Text.Trim()).ToString();
        }
        catch (System.OverflowException)
        {
            MessageBox.Show("Value entered is to large max value: " + Int64.MaxValue.ToString(), "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            this.Text = originalValue;
        }
        catch (System.FormatException)
        {                
            this.Text = originalValue;
        }
        catch (System.Exception ex)
        {
            this.Text = originalValue;
            MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK , MessageBoxIcon.Error);
        }
    }       
}

我会在KeyDown事件中处理它。

void TextBox_KeyDown(object sender, KeyEventArgs e)
        {
            char c = Convert.ToChar(e.PlatformKeyCode);
            if (!char.IsDigit(c))
            {
                e.Handled = true;
            }
        }

通过这个简单的代码，您可以简单地防止添加非数值字符

 if (long.TryParse(TextBox.Text,out long isparsable))
        {
          // your code to handle numbers
        }
        else
        {
            TextBox.Text="Only Numbers Allowed";
            TextBox.Focus();
            TextBox.SelectAll();
        }

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。

在我们的网页与文本框的定义，我们可以添加一个onkeypress事件只接受数字。它不会显示任何消息，但它将防止您输入错误。它为我工作，用户不能输入任何除了数字。

<asp:TextBox runat="server" ID="txtFrom"
     onkeypress="if(isNaN(String.fromCharCode(event.keyCode))) return false;">

这个功能包括复制粘贴，拖放，按下键，防止溢出，非常简单

public partial class IntegerBox : TextBox 
{
    public IntegerBox()
    {
        InitializeComponent();
        this.Text = 0.ToString();
    }

    protected override void OnPaint(PaintEventArgs pe)
    {
        base.OnPaint(pe);
    }

    private String originalValue = 0.ToString();

    private void Integerbox_KeyPress(object sender, KeyPressEventArgs e)
    {
        originalValue = this.Text;
    }

    private void Integerbox_TextChanged(object sender, EventArgs e)
    {
        try
        {
            if(String.IsNullOrWhiteSpace(this.Text))
            {
                this.Text = 0.ToString();
            }
            this.Text = Convert.ToInt64(this.Text.Trim()).ToString();
        }
        catch (System.OverflowException)
        {
            MessageBox.Show("Value entered is to large max value: " + Int64.MaxValue.ToString(), "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            this.Text = originalValue;
        }
        catch (System.FormatException)
        {                
            this.Text = originalValue;
        }
        catch (System.Exception ex)
        {
            this.Text = originalValue;
            MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK , MessageBoxIcon.Error);
        }
    }       
}