ILGenerator.MarkLabel Method
Microsoft Silverlight will reach end of support after October 2021. Learn more.
Marks the Microsoft intermediate language (MSIL) stream's current position with the given label.
Namespace: System.Reflection.Emit
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Overridable Sub MarkLabel ( _
loc As Label _
)
public virtual void MarkLabel(
Label loc
)
Parameters
- loc
Type: System.Reflection.Emit.Label
The label for which to set an index.
Exceptions
| Exception | Condition |
|---|---|
| ArgumentException | loc represents an invalid index into the label array. -or- An index for loc has already been defined. |
Remarks
A label cannot be defined more than once.
Examples
The following example demonstrates the use of MarkLabel to establish the location of a label that was defined earlier. Notice that the label is used in a call to the Emit(OpCode, Label) method overload before its location has been established.
This code is part of a larger example provided for the BeginExceptionBlock method.
adderIL.BeginFinallyBlock()
' The finally block block displays a message on the TextBlock, if the
' OutputBlock field has been set. Just as in the catch block, the following
' code tests whether the TextBlock is present, and skips the output if it is
' not present.
adderIL.Emit(OpCodes.Ldsfld, demoOutput)
adderIL.Emit(OpCodes.Ldnull)
adderIL.Emit(OpCodes.Ceq)
adderIL.Emit(OpCodes.Brtrue_S, skipOutputInFinally)
' Append a constant string to the Text property of the TextBlock.
adderIL.Emit(OpCodes.Ldsfld, demoOutput)
adderIL.Emit(OpCodes.Ldsfld, demoOutput)
adderIL.Emit(OpCodes.Callvirt, getter)
adderIL.Emit(OpCodes.Ldstr, "Executing the finally block." & vbLf)
adderIL.Emit(OpCodes.Call, concat2)
adderIL.Emit(OpCodes.Callvirt, setter)
adderIL.MarkLabel(skipOutputInFinally)
' This is the end of the try/catch/finally block.
adderIL.EndExceptionBlock()
adderIL.BeginFinallyBlock();
// The finally block block displays a message on the TextBlock, if the
// OutputBlock field has been set. Just as in the catch block, the following
// code tests whether the TextBlock is present, and skips the output if it is
// not present.
adderIL.Emit(OpCodes.Ldsfld, demoOutput);
adderIL.Emit(OpCodes.Ldnull);
adderIL.Emit(OpCodes.Ceq);
adderIL.Emit(OpCodes.Brtrue_S, skipOutputInFinally);
// Append a constant string to the Text property of the TextBlock.
adderIL.Emit(OpCodes.Ldsfld, demoOutput);
adderIL.Emit(OpCodes.Ldsfld, demoOutput);
adderIL.Emit(OpCodes.Callvirt, getter);
adderIL.Emit(OpCodes.Ldstr, "Executing the finally block.\n");
adderIL.Emit(OpCodes.Call, concat2);
adderIL.Emit(OpCodes.Callvirt, setter);
adderIL.MarkLabel(skipOutputInFinally);
// This is the end of the try/catch/finally block.
adderIL.EndExceptionBlock();
Version Information
Silverlight
Supported in: 5, 4, 3
Silverlight for Windows Phone
Supported in: Windows Phone OS 7.1
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.