Expression.IfThenElse(Expression, Expression, Expression) Yöntem

Tanım

Ad Alanı:

System.Linq.Expressions

Bütünleştirilmiş Kodlar:

netstandard.dll, System.Linq.Expressions.dll

Kaynak:

ConditionalExpression.cs

ve ConditionalExpression deyimleriyle koşullu bloğu if temsil eden bir else oluşturur.

public:
 static System::Linq::Expressions::ConditionalExpression ^ IfThenElse(System::Linq::Expressions::Expression ^ test, System::Linq::Expressions::Expression ^ ifTrue, System::Linq::Expressions::Expression ^ ifFalse);

public static System.Linq.Expressions.ConditionalExpression IfThenElse(System.Linq.Expressions.Expression test, System.Linq.Expressions.Expression ifTrue, System.Linq.Expressions.Expression ifFalse);

static member IfThenElse : System.Linq.Expressions.Expression * System.Linq.Expressions.Expression * System.Linq.Expressions.Expression -> System.Linq.Expressions.ConditionalExpression

Public Shared Function IfThenElse (test As Expression, ifTrue As Expression, ifFalse As Expression) As ConditionalExpression

Parametreler

test

Expression

Özelliğinin Expression değerine eşit olarak ayarlanması için birTest.

ifTrue

Expression

Özelliğinin Expression değerine eşit olarak ayarlanması için birIfTrue.

ifFalse

Expression

Özelliğinin Expression değerine eşit olarak ayarlanması için birIfFalse.

Döndürülenler

ConditionalExpression

ConditionalExpression özelliğine NodeTypeConditional eşit olan ve Test, IfTrueve IfFalse özellikleri belirtilen değerlere ayarlanmış. Bu yöntem tarafından döndürülen sonucun ConditionalExpression türü: Void.

Örnekler

Aşağıdaki kod örneği, koşullu bloğu temsil eden bir ifadenin nasıl oluşturulacağını gösterir.

// 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.

' 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.