Frequently Used String Extension Methods in C#

Introduction

You may have learned about extension methods in my previous article Extension Method In C# that explained their step-by-step implementation. Therefore, we will now go straight to code. 

Let us see each one by one.

SEO Friendly URL

Here, SEO friendly URL means an URL that has a dash (-) rather than a space between two words and special strings are converted to an appropriate string like C# converts in C#.

1. Create a static class StringExtension that contains an extension method. This extension method converts a title in a SEO friendly URL.
   

   using System.Collections.Generic;
   using System.Text;
   using System.Text.RegularExpressions;
   
   namespace ExtensionMethod
   {
       public static class StringExtension
       {
           public static string SeoFriendlyURL(this string title, int maxLength)
           {
               Dictionary<string, string> dictWords = new Dictionary<string, string>{
                   {"C#","c-sharp"},
                   {"F#","f-sharp"}
               };
   
               foreach (KeyValuePair<string, string> word in dictWords)
               {
                   title = title.Replace(word.Key, word.Value);
               }
   
               var match = Regex.Match(title.ToLower(), "[\\w]+");
               StringBuilder seoUrl = new StringBuilder("");
               bool maxLengthHit = false;
               while (match.Success && !maxLengthHit)
               {
                   if (seoUrl.Length + match.Value.Length <= maxLength)
                   {
                       seoUrl.Append(match.Value + "-");
                   }
                   else
                   {
                       maxLengthHit = true;
                       if (seoUrl.Length == 0)
                       {
                           seoUrl.Append(match.Value.Substring(0, maxLength));
                       }
                   }
                   match = match.NextMatch();
               }
               if (seoUrl[seoUrl.Length - 1] == '-')
               {
                   seoUrl.Remove(seoUrl.Length - 1, 1);
               }
               return seoUrl.ToString();
           }
       }
   }

2. The following code snippet shows how to call it.
   

   using System;
   
   namespace ExtensionMethod
   {
       class Program
       {
           static void Main(string[] args)
           {
               Console.WriteLine("Enter the Title");
               string title = Console.ReadLine();
               string seoUrl = title.SeoFriendlyURL(100);
               Console.WriteLine("Seo url is: {0}", seoUrl);
               Console.ReadKey();
           }
       }
   }

   
   Figure 1.1 : Output for SEO friendly URL

String Exists in String Array

Here we check a string that either exists or not in a defined array.

1. Create a static class StringExtension that contains an extension method. This extension method returns a true value if the string exists in a defined array else returns false.
   

   using System;
   using System.Linq;
   
   namespace ExtensionMethod
   {
       public static class StringExtension
       {
           public static bool IsExist(this string input, params string[] values)
           {
               return String.IsNullOrEmpty(input) ? false : values.Any(S => input.Contains(S));
           }
       }
   }

2. The following code snippet shows how to call it.
   

   using System;
   
   namespace ExtensionMethod
   {
       class Program
       {
           static void Main(string[] args)
           {
               string[] language = new string[] { "C#", "F#", "Java" };
               Console.WriteLine("Enter a lagunage name");
               string name = Console.ReadLine();
               bool isExist = name.IsExist(language);
               Console.WriteLine("{0} is exist: {1}", name, isExist);
               Console.WriteLine("Enter another lagunage name");
                name = Console.ReadLine();
                isExist = name.IsExist(language);
               Console.WriteLine("{0} is exist: {1}", name, isExist);
               Console.ReadKey();
           }
       }
   }

   
   Figure 1.2: Output Extension method

Create Dotted String

Sometimes we have a situation where we don't want to show an entire string, instead we show a portion of a string followed by dots (…).

1. Create a static class StringExtension that contains an extension method. This extension method returns either a dotted string or the full string depending on the conditions.
   

   using System;
   using System.Linq;
   
   namespace ExtensionMethod
   {
       public static class StringExtension
       {
           public static string DottedString(this string input, int length, bool Incomplete = true)
           {
               if (String.IsNullOrEmpty(input))
               {
                   return String.Empty;
               }
               return input.Length > length ? String.Concat(input.Substring(0, length), Incomplete ? "..." : "") : input;
           }
       }
   }

2. The following code snippet shows how to call it.
   

   using System;
   
   namespace ExtensionMethod
   {
       class Program
       {
           static void Main(string[] args)
           {
               Console.WriteLine("Enter a string value");
               string value = Console.ReadLine();
               string dottedString = value.DottedString(5);
               Console.WriteLine("{0} is converted: {1}", value, dottedString);
               Console.WriteLine("Enter another string value");
               value = Console.ReadLine();
               dottedString = value.DottedString(5, false);//trim without dot
               Console.WriteLine("{0} is converted: {1}", value, dottedString);
               Console.ReadKey();
           }
       }
   }

   
   Figure 1.3: Output for dotted string