private void txt3_KeyPress(object sender, KeyPressEventArgs e)
{
    for (int h = 58; h <= 127; h++)
    {
        if (e.KeyChar == h)             //58 to 127 is alphabets tat will be         blocked
        {
            e.Handled = true;
        }
    }
    for(int k=32;k<=47;k++)
    {
        if (e.KeyChar == k)              //32 to 47 are special characters tat will 
        {                                  be blocked
            e.Handled = true;
        }
    }
}

试试这个很简单

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;
            }
        }

很抱歉吵醒死人，但我想有人可能会觉得这对将来的参考有用。

以下是我的处理方法。它处理浮点数，但可以很容易地修改为整数。

基本上你只能按0 - 9和。

前面只能有一个0。

所有其他字符将被忽略，光标位置保持不变。

    private bool _myTextBoxChanging = false;

    private void myTextBox_TextChanged(object sender, EventArgs e)
    {
        validateText(myTextBox);
    }

    private void validateText(TextBox box)
    {
        // stop multiple changes;
        if (_myTextBoxChanging)
            return;
        _myTextBoxChanging = true;

        string text = box.Text;
        if (text == "")
            return;
        string validText = "";
        bool hasPeriod = false;
        int pos = box.SelectionStart;
        for (int i = 0; i < text.Length; i++ )
        {
            bool badChar = false;
            char s = text[i];
            if (s == '.')
            {
                if (hasPeriod)
                    badChar = true;
                else
                    hasPeriod = true;
            }
            else if (s < '0' || s > '9')
                badChar = true;

            if (!badChar)
                validText += s;
            else
            {
                if (i <= pos)
                    pos--;
            }
        }

        // trim starting 00s
        while (validText.Length >= 2 && validText[0] == '0')
        {
            if (validText[1] != '.')
            {
                validText = validText.Substring(1);
                if (pos < 2)
                    pos--;
            }
            else
                break;
        }

        if (pos > validText.Length)
            pos = validText.Length;
        box.Text = validText;
        box.SelectionStart = pos;
        _myTextBoxChanging = false;
    }

下面是一个快速修改的int版本:

    private void validateText(TextBox box)
    {
        // stop multiple changes;
        if (_myTextBoxChanging)
            return;
        _myTextBoxChanging = true;

        string text = box.Text;
        if (text == "")
            return;
        string validText = "";
        int pos = box.SelectionStart;
        for (int i = 0; i < text.Length; i++ )
        {
            char s = text[i];
            if (s < '0' || s > '9')
            {
                if (i <= pos)
                    pos--;
            }
            else
                validText += s;
        }

        // trim starting 00s 
        while (validText.Length >= 2 && validText.StartsWith("00")) 
        { 
            validText = validText.Substring(1); 
            if (pos < 2) 
                pos--; 
        } 

        if (pos > validText.Length)
            pos = validText.Length;
        box.Text = validText;
        box.SelectionStart = pos;
        _myTextBoxChanging = false;
    }

使用Fabio Iotti回答中描述的方法，我创建了一个更通用的解决方案:

public abstract class ValidatedTextBox : TextBox {
    private string m_lastText = string.Empty;
    protected abstract bool IsValid(string text);
    protected sealed override void OnTextChanged(EventArgs e) {
        if (!IsValid(Text)) {
            var pos = SelectionStart - Text.Length + m_lastText.Length;
            Text = m_lastText;
            SelectionStart = Math.Max(0, pos);
        }
        m_lastText = Text;
        base.OnTextChanged(e);
    }
}

"ValidatedTextBox"，它包含了所有重要的验证行为。 剩下要做的就是继承这个类，并使用所需的验证逻辑重写“IsValid”方法。 例如，使用这个类，可以创建"RegexedTextBox"，它只接受匹配特定正则表达式的字符串:

public abstract class RegexedTextBox : ValidatedTextBox {
    private readonly Regex m_regex;
    protected RegexedTextBox(string regExpString) {
        m_regex = new Regex(regExpString);
    }
    protected override bool IsValid(string text) {
        return m_regex.IsMatch(Text);
    }
}

之后，从"RegexedTextBox"类继承，我们可以很容易地创建" positivevenumbertextbox "和"PositiveFloatingPointNumberTextBox"控件:

public sealed class PositiveNumberTextBox : RegexedTextBox {
    public PositiveNumberTextBox() : base(@"^\d*$") { }
}

public sealed class PositiveFloatingPointNumberTextBox : RegexedTextBox {
    public PositiveFloatingPointNumberTextBox()
        : base(@"^(\d+\" + CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator + @")?\d*$") { }
}

不要忘记用户可以在文本框中粘贴无效文本。

如果你想限制它，遵循下面的代码:

private void ultraTextEditor1_TextChanged(object sender, EventArgs e)
{
    string append="";
    foreach (char c in ultraTextEditor1.Text)
    {
        if ((!Char.IsNumber(c)) && (c != Convert.ToChar(Keys.Back)))
        {

        }
        else
        {
            append += c;
        }
    }

    ultraTextEditor1.Text = append;
}