C# List Exists

List type

Exist returns whether a List element is found. You could use a loop and an if-statement. But the Exists method may be clearer in some program contexts. We invoke the Exists method on the List type with a lambda expression.

Lambda Expression

Example

Note

We examine the Exists method on List. This is an instance method that returns true or false depending on whether any element matches the Predicate parameter. The Predicate is a method that returns true or false when passed each element.

Tip:More detailed material on the Predicate type is available. This will help with many methods besides Exists.

Predicate Type
Program that uses Exists method on List: C#

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
	List<int> list = new List<int>();
	list.Add(7);
	list.Add(11);
	list.Add(13);

	// See if any elements with values greater than 10 exist
	bool exists = list.Exists(element => element > 10);
	Console.WriteLine(exists);

	// Check for numbers less than 7
	exists = list.Exists(element => element < 7);
	Console.WriteLine(exists);
    }
}

Output

True
False
True keyword

The example for Exists above tests first to see if any element in the List exists that has a value greater than 10, which returns true. Then it tests for values less than 7, which returns false.

Tip:You can also see the Find method in a separate article. It can be used in many program contexts.

List Find Method

Summary

Framework: NET

In this example, we looked at the Exists instance method on the List type in the C# language and .NET Framework. As a quick way to determine if an element exists, the Exists method is useful in many programs.


C#: Collections: List