How to check if an item exists in a C# list collection?

In C#, you can check if an item exists in a List<T> collection using several methods. The most common approach is the Contains() method, which returns true if the item is found and false otherwise.

Syntax

Following is the syntax for the Contains() method −

bool Contains(T item)

Parameters

• item − The object to locate in the list. The value can be null for reference types.

Return Value

Returns true if the item is found in the list; otherwise, false.

Using Contains() Method

Example

using System;
using System.Collections.Generic;

public class Program {
   public static void Main() {
      List<string> list1 = new List<string>() {
         "Lawrence",
         "Adams",
         "Pitt",
         "Tom"
      };

      Console.WriteLine("List items:");
      foreach(string item in list1) {
         Console.WriteLine(item);
      }

      Console.WriteLine("\nChecking if 'Adams' exists...");
      if (list1.Contains("Adams")) {
         Console.WriteLine("Item exists!");
      } else {
         Console.WriteLine("Item does not exist!");
      }

      Console.WriteLine("\nChecking if 'Smith' exists...");
      if (list1.Contains("Smith")) {
         Console.WriteLine("Item exists!");
      } else {
         Console.WriteLine("Item does not exist!");
      }
   }
}

The output of the above code is −

List items:
Lawrence
Adams
Pitt
Tom

Checking if 'Adams' exists...
Item exists!

Checking if 'Smith' exists...
Item does not exist!

Using Find() Method

The Find() method returns the first element that matches a condition, or the default value if no match is found −

Example

using System;
using System.Collections.Generic;

public class Program {
   public static void Main() {
      List<int> numbers = new List<int>() { 10, 20, 30, 40, 50 };

      int found = numbers.Find(x => x > 25);
      if (found != 0) {
         Console.WriteLine("Found number greater than 25: " + found);
      }

      string notFound = new List<string>() { "Apple", "Banana" }.Find(x => x == "Orange");
      if (notFound != null) {
         Console.WriteLine("Found: " + notFound);
      } else {
         Console.WriteLine("Orange not found in the list");
      }
   }
}

The output of the above code is −

Found number greater than 25: 30
Orange not found in the list

Using Any() Method with LINQ

The Any() method from LINQ checks if any element in the list satisfies a given condition −

Example

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

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

      bool hasLongName = fruits.Any(fruit => fruit.Length > 5);
      Console.WriteLine("Has fruit with name longer than 5 characters: " + hasLongName);

      bool hasApple = fruits.Any(fruit => fruit == "Apple");
      Console.WriteLine("Contains 'Apple': " + hasApple);

      bool hasOrange = fruits.Any(fruit => fruit == "Orange");
      Console.WriteLine("Contains 'Orange': " + hasOrange);
   }
}

The output of the above code is −

Has fruit with name longer than 5 characters: True
Contains 'Apple': True
Contains 'Orange': False

Comparison of Methods

Conclusion

The Contains() method is the simplest way to check if a specific item exists in a C# list. For more complex conditions, use Find() to get the actual item or Any() with LINQ to check existence based on custom criteria.