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.NET Framework Class Library
EnumerableCastTResult Method

Casts the elements of an IEnumerable to the specified type.

Namespace:   System.Linq
Assembly:  System.Core (in System.Core.dll)
Syntax
<[%$TOPIC/bb341406_en-us_VS_110_2_0_0_0_0%]> _
Public Shared Function Cast(Of TResult) ( _
	source As [%$TOPIC/bb341406_en-us_VS_110_2_0_0_0_1%] _
) As [%$TOPIC/bb341406_en-us_VS_110_2_0_0_0_2%](Of TResult)
public static [%$TOPIC/bb341406_en-us_VS_110_2_0_1_0_0%]<TResult> Cast<TResult>(
	this [%$TOPIC/bb341406_en-us_VS_110_2_0_1_0_1%] source
)
[[%$TOPIC/bb341406_en-us_VS_110_2_0_2_0_0%]]
public:
generic<typename TResult>
static [%$TOPIC/bb341406_en-us_VS_110_2_0_2_0_1%]<TResult>^ Cast(
	[%$TOPIC/bb341406_en-us_VS_110_2_0_2_0_2%]^ source
)
static member Cast : 
        source:[%$TOPIC/bb341406_en-us_VS_110_2_0_3_0_0%] -> [%$TOPIC/bb341406_en-us_VS_110_2_0_3_0_1%]<'TResult> 

Type Parameters

TResult

The type to cast the elements of source to.

Parameters

source
Type: System.CollectionsIEnumerable

The IEnumerable that contains the elements to be cast to type TResult.

Return Value

Type: System.Collections.GenericIEnumerableTResult
An IEnumerableT that contains each element of the source sequence cast to the specified type.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).
Exceptions
ExceptionCondition
ArgumentNullException

source is .

InvalidCastException

An element in the sequence cannot be cast to type TResult.

Remarks

This method is implemented by using deferred execution. The immediate return value is an object that stores all the information that is required to perform the action. The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in Visual C# or For Each in Visual Basic.

The CastTResult(IEnumerable) method enables the standard query operators to be invoked on non-generic collections by supplying the necessary type information. For example, ArrayList does not implement IEnumerableT, but by calling CastTResult(IEnumerable) on the ArrayList object, the standard query operators can then be used to query the sequence.

If an element cannot be cast to type TResult, this method will throw an exception. To obtain only those elements that can be cast to type TResult, use the OfTypeTResult method instead of CastTResult(IEnumerable).

In a query expression, an explicitly typed iteration variable translates to an invocation of CastTResult(IEnumerable). This example shows the syntax for an explicitly typed range variable.

from int i in objects
From i As Integer In objects
Examples

The following code example demonstrates how to use CastTResult(IEnumerable) to enable the use of the standard query operators on an ArrayList.

' Create an ArrayList and add items to it. 
Dim fruits As New System.Collections.ArrayList()
fruits.Add("mango")
fruits.Add("apple")
fruits.Add("lemon")

' Call Cast(Of String) to cast the ArrayList elements to strings. 
Dim query As IEnumerable(Of String) = _
    fruits.Cast(Of String)().OrderBy(Function(fruit) fruit).Select(Function(fruit) fruit)

'' The following code, without the cast, doesn't compile. 
'Dim query As IEnumerable(Of String) = _ 
'    fruits.OrderBy(Function(fruit) fruit).Select(Function(fruit) fruit) 

Dim output As New System.Text.StringBuilder
For Each fruit As String In query
    output.AppendLine(fruit)
Next 

' Display the output.
MsgBox(output.ToString())

' This code produces the following output: 
' 
' apple 
' lemon 
' mango
System.Collections.ArrayList fruits = new System.Collections.ArrayList();
fruits.Add("mango");
fruits.Add("apple");
fruits.Add("lemon");

IEnumerable<string> query =
    fruits.Cast<string>().OrderBy(fruit => fruit).Select(fruit => fruit);

// The following code, without the cast, doesn't compile. 
//IEnumerable<string> query1 = 
//    fruits.OrderBy(fruit => fruit).Select(fruit => fruit); 

foreach (string fruit in query)
{
    Console.WriteLine(fruit);
}

// This code produces the following output:  
// 
// apple  
// lemon 
// mango
Version Information

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1
Platforms

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.