Resolved Using regex to restrict a textbox entry

[Tucalipe]

I'm trying to use regex to allow only digits and a single comma on a textbox. However, all of the solutions I've found so far throw an "Unrecognized escape sequence" exception every time I try to build my project.

The last one I've tried is

        private void textBox4_Leave(object sender, EventArgs e)
        {
            if (System.Text.RegularExpressions.Regex.IsMatch(txb_Valor.Text, "(?<=^| )\d+(\.\d+)?(?=$| )"))
            {
                MessageBox.Show("Only numbers please.");
                txb_Valor.Clear();
                txb_Valor.Focus();
            }

What am I doing wrong?

EDIT.: [^0-9,] did the trick.

 

[JohnH]

[^0-9,]

Which means any char not in character class [ 0 to 9 ,] (no repeat)

This should be more like it:

^\d+(,\d+)?$

(one or more digits) followed by optional group (one comma and one or more digits)
^ and $ here match start and end of string

helpful tools:
Regular-Expressions.info - Regex Tutorial, Examples and Reference - Regexp Patterns
Regular Expression Analyzer
.NET Regex Tester - Regex Storm