How to remove an empty string from a list of empty strings in C#?

In C#, you can remove empty strings from a list using several methods. Empty strings can be truly empty ("") or contain only whitespace characters (" "). This article demonstrates different approaches to remove these empty or whitespace-only strings from a list.

Syntax

Using RemoveAll() method to remove empty strings −

list.RemoveAll(string.IsNullOrEmpty);

Using RemoveAll() with lambda expression to remove empty and whitespace strings −

list.RemoveAll(x => string.IsNullOrWhiteSpace(x));

Using LINQ Where() method to filter out empty strings −

var filteredList = list.Where(x => !string.IsNullOrEmpty(x)).ToList();

Using RemoveAll() Method

The RemoveAll() method removes all elements that match the specified condition. This is the most efficient way to remove empty strings directly from the original list −

using System;
using System.Collections.Generic;

class Program {
   static void Main() {
      List<string> myList = new List<string>() {
         "Hello",
         "",
         "World",
         "",
         "C#"
      };

      Console.WriteLine("Original list:");
      foreach (string item in myList) {
         Console.WriteLine("'" + item + "'");
      }

      myList.RemoveAll(string.IsNullOrEmpty);

      Console.WriteLine("\nAfter removing empty strings:");
      foreach (string item in myList) {
         Console.WriteLine("'" + item + "'");
      }
   }
}

The output of the above code is −

Original list:
'Hello'
''
'World'
''
'C#'

After removing empty strings:
'Hello'
'World'
'C#'

Removing Empty and Whitespace Strings

To remove both empty strings and strings containing only whitespace characters, use string.IsNullOrWhiteSpace() −

using System;
using System.Collections.Generic;

class Program {
   static void Main() {
      List<string> myList = new List<string>() {
         "Hello",
         "",
         "   ",
         "World",
         "\t",
         "C#"
      };

      Console.WriteLine("Original list:");
      foreach (string item in myList) {
         Console.WriteLine("'" + item + "'");
      }

      myList.RemoveAll(x => string.IsNullOrWhiteSpace(x));

      Console.WriteLine("\nAfter removing empty and whitespace strings:");
      foreach (string item in myList) {
         Console.WriteLine("'" + item + "'");
      }
   }
}

The output of the above code is −

Original list:
'Hello'
''
'   '
'World'
'	'
'C#'

After removing empty and whitespace strings:
'Hello'
'World'
'C#'

Using LINQ Where() Method

The LINQ Where() method creates a new list with only the non-empty strings, preserving the original list −

using System;
using System.Collections.Generic;
using System.Linq;

class Program {
   static void Main() {
      List<string> originalList = new List<string>() {
         "Apple",
         "",
         "Banana",
         "   ",
         "Cherry"
      };

      Console.WriteLine("Original list count: " + originalList.Count);

      var filteredList = originalList.Where(x => !string.IsNullOrWhiteSpace(x)).ToList();

      Console.WriteLine("Filtered list count: " + filteredList.Count);
      Console.WriteLine("\nFiltered list contents:");
      foreach (string item in filteredList) {
         Console.WriteLine("'" + item + "'");
      }
   }
}

The output of the above code is −

Original list count: 5
Filtered list count: 3

Filtered list contents:
'Apple'
'Banana'
'Cherry'

Comparison of Methods

Conclusion

To remove empty strings from a list in C#, use RemoveAll(string.IsNullOrEmpty) for truly empty strings or RemoveAll(x => string.IsNullOrWhiteSpace(x)) to also remove whitespace-only strings. For preserving the original list, use LINQ's Where() method to create a filtered copy.