Expression.Switch 方法

定義

命名空間:: System.Linq.Expressions

組件:: System.Core.dll, System.Linq.Expressions.dll

組件:: netstandard.dll, System.Linq.Expressions.dll

組件:: System.Linq.Expressions.dll

組件:: System.Core.dll

組件:: netstandard.dll

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

創造一個 SwitchExpression 代表陳述 switch 的。

多載

名稱	Description
Switch(Type, Expression, Expression, MethodInfo, SwitchCase[])	建立 SwitchExpression 一個代表 `switch` 有預設格的陳述。
Switch(Expression, SwitchCase[])	建立 SwitchExpression 一個表示 `switch` 沒有預設格的陳述。
Switch(Expression, Expression, SwitchCase[])	建立 SwitchExpression 一個代表 `switch` 有預設格的陳述。
Switch(Expression, Expression, MethodInfo, IEnumerable<SwitchCase>)	建立 SwitchExpression 一個代表 `switch` 有預設格的陳述。
Switch(Expression, Expression, MethodInfo, SwitchCase[])	建立 SwitchExpression 一個代表 `switch` 有預設格的陳述。
Switch(Type, Expression, Expression, MethodInfo, IEnumerable<SwitchCase>)	建立 SwitchExpression 一個代表 `switch` 有預設格的陳述。

Switch(Type, Expression, Expression, MethodInfo, SwitchCase[])

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

建立 SwitchExpression 一個代表 switch 有預設格的陳述。

public:
 static System::Linq::Expressions::SwitchExpression ^ Switch(Type ^ type, System::Linq::Expressions::Expression ^ switchValue, System::Linq::Expressions::Expression ^ defaultBody, System::Reflection::MethodInfo ^ comparison, ... cli::array <System::Linq::Expressions::SwitchCase ^> ^ cases);

public static System.Linq.Expressions.SwitchExpression Switch(Type type, System.Linq.Expressions.Expression switchValue, System.Linq.Expressions.Expression defaultBody, System.Reflection.MethodInfo comparison, params System.Linq.Expressions.SwitchCase[] cases);

public static System.Linq.Expressions.SwitchExpression Switch(Type? type, System.Linq.Expressions.Expression switchValue, System.Linq.Expressions.Expression? defaultBody, System.Reflection.MethodInfo? comparison, params System.Linq.Expressions.SwitchCase[]? cases);

static member Switch : Type * System.Linq.Expressions.Expression * System.Linq.Expressions.Expression * System.Reflection.MethodInfo * System.Linq.Expressions.SwitchCase[] -> System.Linq.Expressions.SwitchExpression

Public Shared Function Switch (type As Type, switchValue As Expression, defaultBody As Expression, comparison As MethodInfo, ParamArray cases As SwitchCase()) As SwitchExpression

參數

type: Type

切換的結果類型。

switchValue: Expression

要針對每個案例進行檢驗的價值。

defaultBody: Expression

切換 switchValue 結果與任何案例都不符。

comparison: MethodInfo

應採用的平等比較方法。

cases: SwitchCase[]

此切換式的情境集合。

傳回

SwitchExpression

被創造 SwitchExpression的。

適用於

Switch(Expression, SwitchCase[])

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

建立 SwitchExpression 一個表示 switch 沒有預設格的陳述。

public:
 static System::Linq::Expressions::SwitchExpression ^ Switch(System::Linq::Expressions::Expression ^ switchValue, ... cli::array <System::Linq::Expressions::SwitchCase ^> ^ cases);

public static System.Linq.Expressions.SwitchExpression Switch(System.Linq.Expressions.Expression switchValue, params System.Linq.Expressions.SwitchCase[] cases);

public static System.Linq.Expressions.SwitchExpression Switch(System.Linq.Expressions.Expression switchValue, params System.Linq.Expressions.SwitchCase[]? cases);

static member Switch : System.Linq.Expressions.Expression * System.Linq.Expressions.SwitchCase[] -> System.Linq.Expressions.SwitchExpression

Public Shared Function Switch (switchValue As Expression, ParamArray cases As SwitchCase()) As SwitchExpression

參數

switchValue: Expression

要針對每個案例進行檢驗的價值。

cases: SwitchCase[]

此切換式的情境集合。

傳回

SwitchExpression

被創造 SwitchExpression的。

範例

以下範例示範如何建立一個表示式，表示沒有預設案例的 switch 語句。

// Add the following directive to the file:
// using System.Linq.Expressions;

// An expression that represents the switch value.
ConstantExpression switchValue = Expression.Constant(2);

// This expression represents a switch statement
// without a default case.
SwitchExpression switchExpr =
    Expression.Switch(
        switchValue,
        new SwitchCase[] {
            Expression.SwitchCase(
                Expression.Call(
                    null,
                    typeof(Console).GetMethod("WriteLine", new Type[] { typeof(String) }),
                    Expression.Constant("First")
                ),
                Expression.Constant(1)
            ),
            Expression.SwitchCase(
                Expression.Call(
                    null,
                    typeof(Console).GetMethod("WriteLine", new Type[] { typeof(String) }),
                    Expression.Constant("Second")
                ),
                Expression.Constant(2)
            )
        }
    );

// The following statement first creates an expression tree,
// then compiles it, and then runs it.
Expression.Lambda<Action>(switchExpr).Compile()();

// This code example produces the following output:
//
// Second

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

' An expression that represents the switch value.
Dim switchValue As ConstantExpression = Expression.Constant(2)

' This expression represents a switch statement 
' without a default case.
Dim switchExpr As SwitchExpression =
Expression.Switch(
    switchValue,
    New SwitchCase() {
        Expression.SwitchCase(
            Expression.Call(
                Nothing,
                GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}),
                Expression.Constant("First")
            ),
            Expression.Constant(1)
        ),
        Expression.SwitchCase(
            Expression.Call(
                Nothing,
                GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}),
                Expression.Constant("Second")
            ),
            Expression.Constant(2)
        )
    }
)

' The following statement first creates an expression tree,
' then compiles it, and then runs it.
Expression.Lambda(Of Action)(switchExpr).Compile()()

' This code example produces the following output:
'
' Second

備註

物件中SwitchCase的所有SwitchExpression物件必須具有相同的類型，除非具有 SwitchExpressionvoid類型。

每個 SwitchCase 物件都有一個隱 break 含陳述，意即不會有從一個案例標籤到另一個的隱含落差。

若 switchValue 不符合任何情況，則不提出例外。

適用於

Switch(Expression, Expression, SwitchCase[])

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

建立 SwitchExpression 一個代表 switch 有預設格的陳述。

public:
 static System::Linq::Expressions::SwitchExpression ^ Switch(System::Linq::Expressions::Expression ^ switchValue, System::Linq::Expressions::Expression ^ defaultBody, ... cli::array <System::Linq::Expressions::SwitchCase ^> ^ cases);

public static System.Linq.Expressions.SwitchExpression Switch(System.Linq.Expressions.Expression switchValue, System.Linq.Expressions.Expression defaultBody, params System.Linq.Expressions.SwitchCase[] cases);

public static System.Linq.Expressions.SwitchExpression Switch(System.Linq.Expressions.Expression switchValue, System.Linq.Expressions.Expression? defaultBody, params System.Linq.Expressions.SwitchCase[]? cases);

static member Switch : System.Linq.Expressions.Expression * System.Linq.Expressions.Expression * System.Linq.Expressions.SwitchCase[] -> System.Linq.Expressions.SwitchExpression

Public Shared Function Switch (switchValue As Expression, defaultBody As Expression, ParamArray cases As SwitchCase()) As SwitchExpression

參數

switchValue: Expression

要針對每個案例進行檢驗的價值。

defaultBody: Expression

切換 switchValue 結果與任何案例都不符。

cases: SwitchCase[]

此切換式的情境集合。

傳回

SwitchExpression

被創造 SwitchExpression的。

範例

以下範例示範如何建立一個表示式，表示具有預設案例的 switch 語句。

// Add the following directive to the file:
// using System.Linq.Expressions;

// An expression that represents the switch value.
ConstantExpression switchValue = Expression.Constant(3);

// This expression represents a switch statement
// that has a default case.
SwitchExpression switchExpr =
    Expression.Switch(
        switchValue,
        Expression.Call(
                    null,
                    typeof(Console).GetMethod("WriteLine", new Type[] { typeof(String) }),
                    Expression.Constant("Default")
                ),
        new SwitchCase[] {
            Expression.SwitchCase(
                Expression.Call(
                    null,
                    typeof(Console).GetMethod("WriteLine", new Type[] { typeof(String) }),
                    Expression.Constant("First")
                ),
                Expression.Constant(1)
            ),
            Expression.SwitchCase(
                Expression.Call(
                    null,
                    typeof(Console).GetMethod("WriteLine", new Type[] { typeof(String) }),
                    Expression.Constant("Second")
                ),
                Expression.Constant(2)
            )
        }
    );

// The following statement first creates an expression tree,
// then compiles it, and then runs it.
Expression.Lambda<Action>(switchExpr).Compile()();

// This code example produces the following output:
//
// Default

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

' An expression that represents the switch value.
Dim switchValue As ConstantExpression = Expression.Constant(3)

' This expression represents a switch statement 
' that has a default case.
Dim switchExpr As SwitchExpression =
Expression.Switch(
    switchValue,
    Expression.Call(
                Nothing,
                GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}),
                Expression.Constant("Default")
            ),
    New SwitchCase() {
        Expression.SwitchCase(
            Expression.Call(
                Nothing,
                GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}),
                Expression.Constant("First")
            ),
            Expression.Constant(1)
        ),
        Expression.SwitchCase(
            Expression.Call(
                Nothing,
                GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}),
                Expression.Constant("Second")
            ),
            Expression.Constant(2)
        )
    }
)

' The following statement first creates an expression tree,
' then compiles it, and then runs it.
Expression.Lambda(Of Action)(switchExpr).Compile()()

' This code example produces the following output:
'
' Default

備註

物件中SwitchCase的所有SwitchExpression物件必須具有相同的類型，除非具有 SwitchExpressionvoid類型。

每個 SwitchCase 物件都有一個隱 break 含陳述，意即不會有從一個案例標籤到另一個的隱含落差。

若 switchValue 與任何情況不符，則執行所 defaultBody 代表的預設案例。

適用於

Switch(Expression, Expression, MethodInfo, IEnumerable<SwitchCase>)

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

建立 SwitchExpression 一個代表 switch 有預設格的陳述。

public:
 static System::Linq::Expressions::SwitchExpression ^ Switch(System::Linq::Expressions::Expression ^ switchValue, System::Linq::Expressions::Expression ^ defaultBody, System::Reflection::MethodInfo ^ comparison, System::Collections::Generic::IEnumerable<System::Linq::Expressions::SwitchCase ^> ^ cases);

public static System.Linq.Expressions.SwitchExpression Switch(System.Linq.Expressions.Expression switchValue, System.Linq.Expressions.Expression defaultBody, System.Reflection.MethodInfo comparison, System.Collections.Generic.IEnumerable<System.Linq.Expressions.SwitchCase> cases);

public static System.Linq.Expressions.SwitchExpression Switch(System.Linq.Expressions.Expression switchValue, System.Linq.Expressions.Expression? defaultBody, System.Reflection.MethodInfo? comparison, System.Collections.Generic.IEnumerable<System.Linq.Expressions.SwitchCase>? cases);

static member Switch : System.Linq.Expressions.Expression * System.Linq.Expressions.Expression * System.Reflection.MethodInfo * seq<System.Linq.Expressions.SwitchCase> -> System.Linq.Expressions.SwitchExpression

Public Shared Function Switch (switchValue As Expression, defaultBody As Expression, comparison As MethodInfo, cases As IEnumerable(Of SwitchCase)) As SwitchExpression

參數

switchValue: Expression

要針對每個案例進行檢驗的價值。

defaultBody: Expression

切換 switchValue 結果與任何案例都不符。

comparison: MethodInfo

應採用的平等比較方法。

cases: IEnumerable<SwitchCase>

此切換式的情境集合。

傳回

SwitchExpression

被創造 SwitchExpression的。

適用於

Switch(Expression, Expression, MethodInfo, SwitchCase[])

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

建立 SwitchExpression 一個代表 switch 有預設格的陳述。

public:
 static System::Linq::Expressions::SwitchExpression ^ Switch(System::Linq::Expressions::Expression ^ switchValue, System::Linq::Expressions::Expression ^ defaultBody, System::Reflection::MethodInfo ^ comparison, ... cli::array <System::Linq::Expressions::SwitchCase ^> ^ cases);

public static System.Linq.Expressions.SwitchExpression Switch(System.Linq.Expressions.Expression switchValue, System.Linq.Expressions.Expression defaultBody, System.Reflection.MethodInfo comparison, params System.Linq.Expressions.SwitchCase[] cases);

public static System.Linq.Expressions.SwitchExpression Switch(System.Linq.Expressions.Expression switchValue, System.Linq.Expressions.Expression? defaultBody, System.Reflection.MethodInfo? comparison, params System.Linq.Expressions.SwitchCase[]? cases);

static member Switch : System.Linq.Expressions.Expression * System.Linq.Expressions.Expression * System.Reflection.MethodInfo * System.Linq.Expressions.SwitchCase[] -> System.Linq.Expressions.SwitchExpression

Public Shared Function Switch (switchValue As Expression, defaultBody As Expression, comparison As MethodInfo, ParamArray cases As SwitchCase()) As SwitchExpression

參數

switchValue: Expression

要針對每個案例進行檢驗的價值。

defaultBody: Expression

切換 switchValue 結果與任何案例都不符。

comparison: MethodInfo

應採用的平等比較方法。

cases: SwitchCase[]

此切換式的情境集合。

傳回

SwitchExpression

被創造 SwitchExpression的。

適用於

Switch(Type, Expression, Expression, MethodInfo, IEnumerable<SwitchCase>)

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

來源:: SwitchExpression.cs

建立 SwitchExpression 一個代表 switch 有預設格的陳述。

public:
 static System::Linq::Expressions::SwitchExpression ^ Switch(Type ^ type, System::Linq::Expressions::Expression ^ switchValue, System::Linq::Expressions::Expression ^ defaultBody, System::Reflection::MethodInfo ^ comparison, System::Collections::Generic::IEnumerable<System::Linq::Expressions::SwitchCase ^> ^ cases);

public static System.Linq.Expressions.SwitchExpression Switch(Type type, System.Linq.Expressions.Expression switchValue, System.Linq.Expressions.Expression defaultBody, System.Reflection.MethodInfo comparison, System.Collections.Generic.IEnumerable<System.Linq.Expressions.SwitchCase> cases);

public static System.Linq.Expressions.SwitchExpression Switch(Type? type, System.Linq.Expressions.Expression switchValue, System.Linq.Expressions.Expression? defaultBody, System.Reflection.MethodInfo? comparison, System.Collections.Generic.IEnumerable<System.Linq.Expressions.SwitchCase>? cases);

static member Switch : Type * System.Linq.Expressions.Expression * System.Linq.Expressions.Expression * System.Reflection.MethodInfo * seq<System.Linq.Expressions.SwitchCase> -> System.Linq.Expressions.SwitchExpression

Public Shared Function Switch (type As Type, switchValue As Expression, defaultBody As Expression, comparison As MethodInfo, cases As IEnumerable(Of SwitchCase)) As SwitchExpression