Expression.IfThenElse Method
.NET Framework 4.5
Creates a ConditionalExpression that represents a conditional block with if and else statements.
Namespace: System.Linq.Expressions
Assembly: System.Core (in System.Core.dll)
public static ConditionalExpression IfThenElse( Expression test, Expression ifTrue, Expression ifFalse )
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: // using System.Linq.Expressions; bool test = true; // This expression represents the conditional block. Expression ifThenElseExpr = Expression.IfThenElse( Expression.Constant(test), Expression.Call( null, typeof(Console).GetMethod("WriteLine", new Type[] { typeof(String) }), Expression.Constant("The condition is true.") ), Expression.Call( null, typeof(Console).GetMethod("WriteLine", new Type[] { typeof(String) }), Expression.Constant("The condition is false.") ) ); // The following statement first creates an expression tree, // then compiles it, and then runs it. Expression.Lambda<Action>(ifThenElseExpr).Compile()(); // This code example produces the following output: // // The condition is true.
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.
