C# Regular Expression - Regular Expression in C#



C# Regular Expression - Regular Expression in C#

Regular Expression
  • In C#, Regular Expression is used for the parsing and validation of the given text to match with the defined pattern for example, an email address.
  • The pattern can contain characters, operators, literals and constructs.
  • Generally, we used the regular expression engine, to process the text with the regular Expression in .NET Framework.
  • Regular Expression is shown by the Regex, in C#.
  • We used the Regular Expression to check whether the given string matches the pattern or not.
  • Regex or Regular Expression is a sequence of characters that defines the pattern.
  • The pattern can contain literals, characters, numbers, operators, etc.
  • We used the Patterns to search the strings or files and here we will see if the matches are found or not.
  • Generally, the Regular Expressions are used for the parsing, finding the validations or strings, etc.

Regex Class

  • In .NET Framework regex class shows the regular expression engine.
  • This class is used to parse a large amount of text for finding the specific character pattern.
  • We can use this class for the extraction, editing, for the replacement, or to delete the text of the substring.
  • Regex Class has the string pattern as a parameter with the other optional parameter and System.Text.RegularExpressions namespace contains the Regex class.

Create a pattern for the word that starts with letter "M"

string pattern = @"\b[M]\w+";  

Create a Regex

Regex rgex = new Regex(pattern); 

Create a Long string

string authors = "Ramesh chand, Rakeshwar"; 

Get all matches

MatchCollection matchedAuthors = rg.Matches(authors);  
To find the matches collection we will use the For loop // Print all matched authors    
for (int count = 0; count < matchedAuthors.Count; count++)    
Console.WriteLine(matchedAuthors[count]. Value); 

For print all matched authors

for (int count = 0; count < matchedAuthors.Count; count++)    
Console.WriteLine(matchedAuthors[count].Value);

Sample Code

using System;
using System.Text.RegularExpressions;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello Wikitechy!");
            string email = "[email protected]";

            var result = Regex.IsMatch(email, @"^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$");

            Console.Write("Is valid: {0} ", result);

            Console.ReadLine();
        }
    }
}

Output

Regular Expression

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