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TraceListener Class

Provides the abstract base class for the listeners who monitor trace and debug output.

Namespace: System.Diagnostics
Assembly: System (in system.dll)

public abstract class TraceListener : MarshalByRefObject, IDisposable
public abstract class TraceListener extends MarshalByRefObject implements IDisposable
public abstract class TraceListener extends MarshalByRefObject implements IDisposable

NoteNote

The HostProtectionAttribute attribute applied to this class has the following Resources property value: Synchronization. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

For examples of how to implement a TraceListener, see the DefaultTraceListener, TextWriterTraceListener and the EventLogTraceListener classes.

You must enable tracing or debugging to use a trace listener. The following syntax is compiler specific. If you use compilers other than C# or Visual Basic, refer to the documentation for your compiler.

  • To enable debugging in C#, add the /d:DEBUG flag to the compiler command line when you compile your code, or you can add #define DEBUG to the top of your file. In Visual Basic, add the /d:DEBUG=True flag to the compiler command line.

  • To enable tracing in C#, add the /d:TRACE flag to the compiler command line when you compile your code, or add #define TRACE to the top of your file. In Visual Basic, add the /d:TRACE=True flag to the compiler command line.

To add a trace listener, edit the configuration file that corresponds to the name of your application. Within this file, you can add a listener, set its type and set its parameter, remove a listener, or clear all the listeners previously set by the application. The configuration file should be formatted similar to the following example.

<configuration>
  <system.diagnostics>
    <trace autoflush="false" indentsize="4">
      <listeners>
        <add name="myListener" type="System.Diagnostics.TextWriterTraceListener" initializeData="TextWriterOutput.log" />
        <remove name="Default" />
      </listeners>
    </trace>
  </system.diagnostics>
</configuration>

For more information on using configuration files for tracing, see <system.diagnostics> Element.

Notes to Inheritors Inherit from this class to implement a custom listener for the Debug and Trace classes. At a minimum, you must implement the Write and WriteLine methods. Additionally, you can implement the Fail, Close and Flush methods.

This type is safe for multithreaded operations.

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0
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