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Expression.Switch Method (Expression, SwitchCase())

Creates a SwitchExpression that represents a switch statement without a default case.

Namespace:  System.Linq.Expressions
Assemblies:   System.Core (in System.Core.dll)
  System.Linq.Expressions (in System.Linq.Expressions.dll)

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

Parameters

switchValue
Type: System.Linq.Expressions.Expression

The value to be tested against each case.

cases
Type: System.Linq.Expressions.SwitchCase()

The set of cases for this switch expression.

All SwitchCase objects in a SwitchExpression object must have the same type, unless the SwitchExpression has the type void.

Each SwitchCase object has an implicit break statement, which means that there is no implicit fall through from one case label to another.

If switchValue does not match any of the cases, no exception is thrown.

The following example demonstrates how to create an expression that represents a swtich statement without a default case.

' 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

.NET Framework

Supported in: 4.6, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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