Condition Method (Expression, Expression, Expression)
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Expression.Condition Method (Expression, Expression, Expression)

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Creates a ConditionalExpression that represents a conditional statement.

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

'Declaration
Public Shared Function Condition ( _
	test As Expression, _
	ifTrue As Expression, _
	ifFalse As Expression _
) As ConditionalExpression

Parameters

test
Type: System.Linq.Expressions.Expression
An Expression to set the Test property equal to.
ifTrue
Type: System.Linq.Expressions.Expression
An Expression to set the IfTrue property equal to.
ifFalse
Type: System.Linq.Expressions.Expression
An Expression to set the IfFalse property equal to.

Return Value

Type: System.Linq.Expressions.ConditionalExpression
A ConditionalExpression that has the NodeType property equal to Conditional and the Test, IfTrue, and IfFalse properties set to the specified values.

ExceptionCondition
ArgumentNullException

test or ifTrue or ifFalse is Nothing.

ArgumentException

test.Type is not Boolean.

-or-

ifTrue.Type is not equal to ifFalse.Type.

The Type property of the resulting ConditionalExpression is equal to the Type property of ifTrue.

The following code example shows how to create an expression that represents a conditional statement. If the first argument evaluates to true, the second argument is executed; otherwise, the third argument is executed.


' Add the following directive to your file:
' Imports System.Linq.Expressions  

Dim num As Integer = 100

' This expression represents a conditional operation; 
' it will evaluate the test (first expression) and
' execute the ifTrue block (second argument) if the test evaluates to true, 
' or the ifFalse block (third argument) if the test evaluates to false.
Dim conditionExpr As Expression = Expression.Condition(
                            Expression.Constant(num > 10),
                            Expression.Constant("n is greater than 10"),
                            Expression.Constant("n is smaller than 10")
                        )

' Print the expression.
outputBlock.Text &= conditionExpr.ToString() & vbCrLf

' The following statement first creates an expression tree,
' then compiles it, and then executes it.       
outputBlock.Text &=
    Expression.Lambda(Of Func(Of String))(conditionExpr).Compile()() & vbCrLf

' This code example produces the following output:
'
' IIF("True", "num is greater than 10", "num is smaller than 10")
' num is greater than 10


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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