Export (0) Print
Expand All

Expression.Label Method

Creates a LabelTarget representing a label with void type and no name.

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

public static LabelTarget Label()

Return Value

Type: System.Linq.Expressions.LabelTarget
The new LabelTarget representing a label with void type and no name.

The following example demonstrates how to create an expression that contains a LabelTarget object.


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

// A label expression of the void type that is the target for Expression.Return().
LabelTarget returnTarget = Expression.Label();

// This block contains a GotoExpression that represents a return statement with no value.
// It transfers execution to a label expression that is initialized with the same LabelTarget as the GotoExpression.
// The types of the GotoExpression, label expression, and LabelTarget must match.
BlockExpression blockExpr =
    Expression.Block(
        Expression.Call(typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) }), Expression.Constant("Return")),
        Expression.Return(returnTarget),
        Expression.Call(typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) }), Expression.Constant("Other Work")),
        Expression.Label(returnTarget)
    );

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

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

// "Other Work" is not printed because 
// the Return expression transfers execution from Expression.Return(returnTarget)
// to Expression.Label(returnTarget).


Silverlight

Supported in: 5, 4

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Community Additions

ADD
Show:
© 2014 Microsoft