What are regular expressions in C#

Regular expression is a pattern that could be matched against an input text. The .NET framework provides a regular expression engine that allows such matching. A pattern consists of one or more character literals, operators, or constructs.

For example, if you want to match words that begin with ‘S’, use Regular Expressions in C# as shown in the following code −

Example

using System;
using System.Text.RegularExpressions;

namespace Demo {
   class Program {
      private static void showMatch(string text, string expr) {
         Console.WriteLine("The Expression: " + expr);
         MatchCollection mc = Regex.Matches(text, expr);

         foreach (Match m in mc) {
            Console.WriteLine(m);
         }
      }
      static void Main(string[] args) {
         string str = "Email Sent Today!";

         Console.WriteLine("Matching words that start with 'S': ");
         showMatch(str, @"\bS\S*");
         Console.ReadKey();
      }
   }
}

Output

Matching words that start with 'S':
The Expression: \bS\S*
Sent

The Regex class for regular expressions in C# has the following methods: