using System;
using System.Text.RegularExpressions;
class RegexSubstitution
{
public static void Main()
{
string testString1 = "1, 2, 3, 4, 5, 6, 7, 8";
Regex testRegex1 = new Regex( @"\d" );
Console.WriteLine( "Original string: " + testString1 );
Console.WriteLine( "Replace first 3 digits by \"digit\": " + testRegex1.Replace( testString1, "digit", 3 ) );
}
}