Expression.TypeAs Method (System.Linq.Expressions)

MSDN Library
.NET Development
.NET Framework 3.5
.NET Framework Class Library
System.Linq.Expressions Namespace
Expression Class
Expression Methods

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Subtract Method
SubtractChecked Method
ToString Method

TypeAs Method

TypeIs Method
UnaryPlus Method

Expression..::.TypeAs Method
This page is specific to:.NET Framework Version:3.5Silverlight 3 4.0

.NET Framework Class Library

Expression..::.TypeAs Method

Creates a UnaryExpression that represents an explicit reference or boxing conversion where nullNothingnullptra null reference (Nothing in Visual Basic) is supplied if the conversion fails.

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

Syntax

C++

JScript

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'Usage

Dim expression As Expression
Dim type As Type
Dim returnValue As UnaryExpression

returnValue = Expression.TypeAs(expression, _
    type)

'Declaration

Public Shared Function TypeAs ( _
    expression As Expression, _
    type As Type _
) As UnaryExpression

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.

Exceptions

Exception	Condition
ArgumentNullException	expression or type is nullNothingnullptra null reference (Nothing in Visual Basic).

Remarks

The Method property of the resulting UnaryExpression is nullNothingnullptra null reference (Nothing in Visual Basic). The IsLifted and IsLiftedToNull properties are both false.

Examples

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.

C++

JScript

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' Create a UnaryExpression that represents a reference
' conversion of an Integer to an Integer? (a nullable Integer).
Dim typeAsExpression As System.Linq.Expressions.UnaryExpression = _
    System.Linq.Expressions.Expression.TypeAs( _
        System.Linq.Expressions.Expression.Constant(34, Type.GetType("System.Int32")), _
        Type.GetType("System.Nullable`1[System.Int32]"))

Console.WriteLine(typeAsExpression.ToString())

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

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

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

Version Information

.NET Framework

Supported in: 3.5

Reference

Expression Class

Expression Members

System.Linq.Expressions Namespace