Expression.IfThenElse(Expression, Expression, Expression) 메서드

정의

네임스페이스:

System.Linq.Expressions

어셈블리:

System.Linq.Expressions.dll

Source:

ConditionalExpression.cs

ConditionalExpression 및 if 문을 사용하여 조건부 블록을 나타내는 else을 만듭니다.

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

매개 변수

test

Expression

Expression 속성에 설정할 Test입니다.

ifTrue

Expression

Expression 속성에 설정할 IfTrue입니다.

ifFalse

Expression

Expression 속성에 설정할 IfFalse입니다.

반환

ConditionalExpression

ConditionalExpression 속성이 NodeType이고 Conditional, Test 및 IfTrue 속성이 지정된 값으로 설정된 IfFalse입니다. 이 메서드에서 반환되는 결과 ConditionalExpression의 형식은 Void입니다.

예제

다음 코드 예제에서는 조건부 블록을 나타내는 식을 만드는 방법을 보여 줍니다.

// 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.