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 ) ); } }