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;
    }

这正是设计已验证/正在验证事件的目的。

下面是MSDN上关于这个主题的文章:http://msdn.microsoft.com/en-us/library/system.windows.forms.control.validating.aspx

TL;DR版本:检查validate事件中的. text属性，并在数据无效时设置e.Cancel=True。

当你设置e.Cancel=True时，用户不能离开这个字段，但是你需要给他们一些错误的反馈。我将方框的背景颜色更改为浅红色，以表示有问题。确保将其设置回SystemColors。窗口时调用一个良好的值。

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。

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();
        }

我从上下文和您使用的标记假设您正在编写一个。net c#应用程序。在这种情况下，您可以订阅文本更改事件，并验证每个按键。

private void textBox1_TextChanged(object sender, EventArgs e)
{
    if (System.Text.RegularExpressions.Regex.IsMatch(textBox1.Text, "[^0-9]"))
    {
        MessageBox.Show("Please enter only numbers.");
        textBox1.Text = textBox1.Text.Remove(textBox1.Text.Length - 1);
    }
}

两个选择:

Use a NumericUpDown instead. NumericUpDown does the filtering for you, which is nice. Of course it also gives your users the ability to hit the up and down arrows on the keyboard to increment and decrement the current value. Handle the appropriate keyboard events to prevent anything but numeric input. I've had success with this two event handlers on a standard TextBox: private void textBox1_KeyPress(object sender, KeyPressEventArgs e) { if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar) && (e.KeyChar != '.')) { e.Handled = true; } // only allow one decimal point if ((e.KeyChar == '.') && ((sender as TextBox).Text.IndexOf('.') > -1)) { e.Handled = true; } }

您可以删除'的支票。如果你的文本框不允许小数点，'(和后续检查不止一个'.')。你也可以添加一个检查'-'如果你的文本框应该允许负值。

如果您想限制用户的位数，请使用:textBox1。MaxLength = 2;//这将允许用户只输入2位数字