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Queryable.Count<TSource> Method (IQueryable<TSource>)

 

Returns the number of elements in a sequence.

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

public static int Count<TSource>(
	this IQueryable<TSource> source
)

Parameters

source
Type: System.Linq.IQueryable<TSource>

The IQueryable<T> that contains the elements to be counted.

Return Value

Type: System.Int32

The number of elements in the input sequence.

Type Parameters

TSource

The type of the elements of source.

Exception Condition
ArgumentNullException

source is null.

OverflowException

The number of elements in source is larger than MaxValue.

The Count<TSource>(IQueryable<TSource>) method generates a MethodCallExpression that represents calling Count<TSource>(IQueryable<TSource>) itself as a constructed generic method. It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling Count<TSource>(IQueryable<TSource>) depends on the implementation of the type of the source parameter. The expected behavior is that it counts the number of items in source.

The following code example demonstrates how to use Count<TSource>(IQueryable<TSource>) to count the elements in a sequence.

string[] fruits = { "apple", "banana", "mango", 
                    "orange", "passionfruit", "grape" };

int numberOfFruits = fruits.AsQueryable().Count();

Console.WriteLine(
    "There are {0} items in the array.",
    numberOfFruits);

// This code produces the following output:
//
// There are 6 items in the array. 

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.1
Windows Phone
Available since 8.1
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