Regular Expression in C# with Examples

A 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.

Let’s see how to split a regular expression.

To split a string using regular expression, use the Regex.split.

Let’s say our string is −

string str = "Hello\r\nWorld";

Now use Regex.split to split the string as shown below −

string[] res = Regex.Split(str, "\r\n");

The following is the complete code to split a string using Regular Expression in C# −

Example

using System;
using System.Text.RegularExpressions;

class Demo {
   static void Main() {
      string str = "Hello\r\nWorld";

      string[] res = Regex.Split(str, "\r\n");

      foreach (string word in res) {
         Console.WriteLine(word);
      }
   }
}

Let us now see an example to remove extra whitespace.

Example

using System;
using System.Text.RegularExpressions;

namespace RegExApplication {
   class Program {
      static void Main(string[] args) {
         string input = "Hello World ";
         string pattern = "\\s+";
         string replacement = " ";

         Regex rgx = new Regex(pattern);
         string result = rgx.Replace(input, replacement);
   
         Console.WriteLine("Original String: {0}", input);
         Console.WriteLine("Replacement String: {0}", result);
         Console.ReadKey();
      }
   }
}