Expression.IfThenElse Method (Expression, Expression, Expression)
.NET Framework (current version)
Creates a ConditionalExpression that represents a conditional block with if and else statements.
Assembly: System.Core (in System.Core.dll)
Public Shared Function IfThenElse ( 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.ConditionalExpressionA ConditionalExpression that has the NodeType property equal to Conditional and the Test, IfTrue, and IfFalse properties set to the specified values. The type of the resulting ConditionalExpression returned by this method is Void.
The following code example shows how to create an expression that represents a conditional block.
' Add the following directive to the file: ' Imports System.Linq.Expressions Dim test As Boolean = True ' This expression represents the conditional block. Dim ifThenElseExpr As Expression = Expression.IfThenElse( Expression.Constant(test), Expression.Call( Nothing, GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}), Expression.Constant("The condition is true.") ), Expression.Call( Nothing, GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}), Expression.Constant("The condition is false.") ) ) ' The following statement first creates an expression tree, ' then compiles it, and then runs it. Expression.Lambda(Of Action)(ifThenElseExpr).Compile()() ' This code example produces the following output: ' ' The condition is true.
Universal Windows Platform
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 4.0
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 4.0
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
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