using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"\.\d+(*SKIP)(*FAIL)|\B(?=(?:\d{3})+(?!\d))";
string substitution = @",";
string input = @"123456789.1
123456789
1.1
10.1
100.1
1000.1
10000.11
100000.1111111111
1000000.111
10000000.11111.1111
100000000.111111
1000000000.1111111
123456789
1
10
100
1000
10000
100000
1000000
10000000
100000000
1000000000";
RegexOptions options = RegexOptions.Multiline;
Regex regex = new Regex(pattern, options);
string result = regex.Replace(input, substitution);
}
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx