using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"\b(?<!-)(?:\d{1,2}|100)\b";
string substitution = @"-";
string input = @"Sam has 200 apples. He gives Todd 20 and Mary 125.
The weather is -5 C today, but will be +5 C tomorrow.";
RegexOptions options = RegexOptions.Multiline | RegexOptions.IgnoreCase;
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