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;
            }
        }

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;">

最简单粗暴的方法是使用组合框而不是带有只读的文本框。当然，只有当你希望用户使用一个合理的整数集，而不是试图接近无穷大时，它才有用。

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

似乎目前对这个问题的许多答案都是手动解析输入文本。如果你正在寻找一个特定的内置数字类型(例如int或double)，为什么不只是将工作委托给该类型的TryParse方法?例如:

public class IntTextBox : TextBox
{
    string PreviousText = "";
    int BackingResult;

    public IntTextBox()
    {
        TextChanged += IntTextBox_TextChanged;
    }

    public bool HasResult { get; private set; }

    public int Result
    {
        get
        {
            return HasResult ? BackingResult : default(int);
        }
    }

    void IntTextBox_TextChanged(object sender, EventArgs e)
    {
        HasResult = int.TryParse(Text, out BackingResult);

        if (HasResult || string.IsNullOrEmpty(Text))
        {
            // Commit
            PreviousText = Text;
        }
        else
        {
            // Revert
            var changeOffset = Text.Length - PreviousText.Length;
            var previousSelectionStart =
                Math.Max(0, SelectionStart - changeOffset);

            Text = PreviousText;
            SelectionStart = previousSelectionStart;
        }
    }
}

如果你想要更通用但仍然兼容Visual Studio的设计器:

public class ParsableTextBox : TextBox
{
    TryParser BackingTryParse;
    string PreviousText = "";
    object BackingResult;

    public ParsableTextBox()
        : this(null)
    {
    }

    public ParsableTextBox(TryParser tryParse)
    {
        TryParse = tryParse;

        TextChanged += ParsableTextBox_TextChanged;
    }

    public delegate bool TryParser(string text, out object result);

    public TryParser TryParse
    {
        set
        {
            Enabled = !(ReadOnly = value == null);

            BackingTryParse = value;
        }
    }

    public bool HasResult { get; private set; }

    public object Result
    {
        get
        {
            return GetResult<object>();
        }
    }

    public T GetResult<T>()
    {
        return HasResult ? (T)BackingResult : default(T);
    }

    void ParsableTextBox_TextChanged(object sender, EventArgs e)
    {
        if (BackingTryParse != null)
        {
            HasResult = BackingTryParse(Text, out BackingResult);
        }

        if (HasResult || string.IsNullOrEmpty(Text))
        {
            // Commit
            PreviousText = Text;
        }
        else
        {
            // Revert
            var changeOffset = Text.Length - PreviousText.Length;
            var previousSelectionStart =
                Math.Max(0, SelectionStart - changeOffset);

            Text = PreviousText;
            SelectionStart = previousSelectionStart;
        }
    }
}

最后，如果你想要完全通用的东西，不关心Designer支持:

public class ParsableTextBox<T> : TextBox
{
    TryParser BackingTryParse;
    string PreviousText;
    T BackingResult;

    public ParsableTextBox()
        : this(null)
    {
    }

    public ParsableTextBox(TryParser tryParse)
    {
        TryParse = tryParse;

        TextChanged += ParsableTextBox_TextChanged;
    }

    public delegate bool TryParser(string text, out T result);

    public TryParser TryParse
    {
        set
        {
            Enabled = !(ReadOnly = value == null);

            BackingTryParse = value;
        }
    }

    public bool HasResult { get; private set; }

    public T Result
    {
        get
        {
            return HasResult ? BackingResult : default(T);
        }
    }

    void ParsableTextBox_TextChanged(object sender, EventArgs e)
    {
        if (BackingTryParse != null)
        {
            HasResult = BackingTryParse(Text, out BackingResult);
        }

        if (HasResult || string.IsNullOrEmpty(Text))
        {
            // Commit
            PreviousText = Text;
        }
        else
        {
            // Revert
            var changeOffset = Text.Length - PreviousText.Length;
            var previousSelectionStart =
                Math.Max(0, SelectionStart - changeOffset);

            Text = PreviousText;
            SelectionStart = previousSelectionStart;
        }
    }
}

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);
    }
}