仅包含数字的文本框 [英] TextBox with only numbers

问题描述

我需要创建一个仅包含数字的TextBox，但是我做不到.我试过了:InputScope ="Numbers"，但这仅适用于Mobile.我也尝试过 TextChanging :

I need to create a TextBox with only numbers but I couldn't do. I have tried to put : InputScope = "Numbers" but this only work on Mobile. Also I have tried on TextChanging this:

private void textBox1_TextChanged(object sender, EventArgs e)
{
    if (System.Text.RegularExpressions.Regex.IsMatch(textBox1.Text, "[^0-9]"))
    {

        textBox1.Text = textBox1.Text.Remove(textBox1.Text.Length - 1);
    }
}

推荐答案

您可以阻止任何非数字输入，也可以只过滤掉文本中的数字.

You can either prevent any non-numeric input whatsoever, or just filter out digits in the text.

防止非数字输入

使用 BeforeTextChanging 事件:

<TextBox BeforeTextChanging="TextBox_OnBeforeTextChanging" />

现在处理如下:

private void TextBox_OnBeforeTextChanging(TextBox sender,
                                          TextBoxBeforeTextChangingEventArgs args)
{
    args.Cancel = args.NewText.Any(c => !char.IsDigit(c));
}

此LINQ表达式将返回 true ，因此，如果输入中遇到任何非数字字符，则取消更改文本.

This LINQ expression will return true and hence Cancel the text change in case it encounters any non-digit character in the input.

过滤非数字输入

使用 TextChanging 事件:

<TextBox TextChanging="TextBox_OnTextChanging" /> 

并以这种方式处理:

private void TextBox_OnTextChanging(TextBox sender, TextBoxTextChangingEventArgs args)
{
    //Save the position of the selection, to prevent the cursor to jump to the start
    int pos = sender.SelectionStart;
    sender.Text = new String(sender.Text.Where(char.IsDigit).ToArray());
    sender.SelectionStart = pos;
}

此LINQ查询将过滤掉非数字字符并仅使用输入中的数字来创建新的 string .

This LINQ query will filter out non-digit characters and create a new string only with the digits in the input.

最好使用 TextChanging 和 BeforeTextChanging ，因为 TextChanged 发生得太晚了，所以看到临时显示的字符会使用户感到困惑在屏幕上，然后立即消失.

It is preferable to use TextChanging and BeforeTextChanging, because TextChanged occurs too late, so the user would be confused by seeing characters temporarily display on the screen and immediately disappearing.

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