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Expression.TypeAs Method

Creates a UnaryExpression that represents an explicit reference or boxing conversion where null is supplied if the conversion fails.

Namespace:  System.Linq.Expressions
Assembly:  System.Core (in System.Core.dll)
public static UnaryExpression TypeAs(
	Expression expression,
	Type type
)

Parameters

expression
Type: System.Linq.Expressions.Expression

An Expression to set the Operand property equal to.

type
Type: System.Type

A Type to set the Type property equal to.

Return Value

Type: System.Linq.Expressions.UnaryExpression
A UnaryExpression that has the NodeType property equal to TypeAs and the Operand and Type properties set to the specified values.
ExceptionCondition
ArgumentNullException

expression or type is null.

The Method property of the resulting UnaryExpression is null. The IsLifted and IsLiftedToNull properties are both false.

The following example demonstrates how to use the TypeAs(Expression, Type) method to create a UnaryExpression that represents the reference conversion of a non-nullable integer expression to the nullable integer type.

// Create a UnaryExpression that represents a 
// conversion of an int to an int?.
System.Linq.Expressions.UnaryExpression typeAsExpression =
    System.Linq.Expressions.Expression.TypeAs(
        System.Linq.Expressions.Expression.Constant(34, typeof(int)),
        typeof(int?));

Console.WriteLine(typeAsExpression.ToString());

// This code produces the following output: 
// 
// (34 As Nullable`1)

.NET Framework

Supported in: 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

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.

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