Enumerable.Any<TSource> Method (IEnumerable<TSource>)

May 11, 2014

Determines whether a sequence contains any elements.

Namespace:  System.Linq
Assembly:  System.Core (in System.Core.dll)

public static bool Any<TSource>(
	this IEnumerable<TSource> source
)

Type Parameters

TSource

The type of the elements of source.

Parameters

source
Type: System.Collections.Generic.IEnumerable<TSource>
The IEnumerable<T> to check for emptiness.

Return Value

Type: System.Boolean
true if the source sequence contains any elements; otherwise, false.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<TSource>. When you use instance method syntax to call this method, omit the first parameter.

ExceptionCondition
ArgumentNullException

source is null.

NoteNote:

This method does not return any one element of a collection. Instead, it determines whether the collection contains any elements.

The enumeration of source is stopped as soon as the result can be determined.

In Visual Basic query expression syntax, an Aggregate Into Any() clause translates to an invocation of Enumerable.Any.

The following code example demonstrates how to use Any to determine whether a sequence contains any elements.


         List<int> numbers = new List<int> { 1, 2 };
         bool hasElements = numbers.Any();

         outputBlock.Text += String.Format("The list {0} empty.",
             hasElements ? "is not" : "is") + "\n";

         // This code produces the following output:
         //
         // The list is not empty. 



The Boolean value that the Any<TSource>(IEnumerable<TSource>) method returns is typically used in the predicate of a where clause (Where clause in Visual Basic) or a direct call to the Where<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>) method. The following example demonstrates this use of the Any method.


class Pet
{
   public string Name { get; set; }
   public int Age { get; set; }
}
class Person
{
   public string LastName { get; set; }
   public Pet[] Pets { get; set; }
}

public static void AnyEx2()
{
   List<Person> people = new List<Person>
           { new Person { LastName = "Haas",
                          Pets = new Pet[] { new Pet { Name="Barley", Age=10 },
                                             new Pet { Name="Boots", Age=14 },
                                             new Pet { Name="Whiskers", Age=6 }}},
             new Person { LastName = "Fakhouri",
                          Pets = new Pet[] { new Pet { Name = "Snowball", Age = 1}}},
             new Person { LastName = "Antebi",
                          Pets = new Pet[] { }},
             new Person { LastName = "Philips",
                          Pets = new Pet[] { new Pet { Name = "Sweetie", Age = 2},
                                             new Pet { Name = "Rover", Age = 13}} }
           };

   // Determine which people have a non-empty Pet array.
   IEnumerable<string> names = from person in people
                               where person.Pets.Any()
                               select person.LastName;

   foreach (string name in names)
   {
      outputBlock.Text += name + "\n";
   }

   /* This code produces the following output:

      Haas
      Fakhouri
      Philips
   */
}


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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