You can use the properties and methods in the Trace class to instrument release builds. Instrumentation allows you to monitor the health of your application running in real-life settings. Tracing helps you isolate problems and fix them without disturbing a running system.

This class provides methods to display an Assert dialog box, and to emit an assertion that will always Fail. This class provides write methods in the following variations: Write, WriteLine, WriteIf, and WriteLineIf.

The BooleanSwitch and TraceSwitch classes provide means to dynamically control the tracing output. You can modify the values of these switches without recompiling your application. For information on using the configuration file to set a switch, see the Switch class and the How to: Configure Trace Switches topic.

You can customize the tracing output's target by adding TraceListener instances to or removing instances from the Listeners collection. By default, trace output is emitted using the DefaultTraceListener class.

Note:

Adding a trace listener to the Listeners collection can cause an exception to be thrown while tracing, if a resource used by the trace listener is not available. The conditions and the exception thrown depend on the trace listener and cannot be enumerated in this topic. It may be useful to place calls to the Trace methods in try/catch blocks to detect and handle any exceptions from trace listeners.

The Trace class provides properties to get or set the level of Indent, the IndentSize, and whether to AutoFlush after each write.

To set the AutoFlush and IndentSize for Trace, you can edit the configuration file that corresponds to the name of your application. The configuration file should be formatted like the following example:

<configuration>
  <system.diagnostics>
    <trace autoflush="false" indentsize="3" />
  </system.diagnostics>
</configuration>

The ConditionalAttribute attribute is applied to the methods of Trace. Compilers that support ConditionalAttribute ignore calls to these methods unless "TRACE" is defined as a conditional compilation symbol. Refer to a compiler's documentation to determine whether ConditionalAttribute is supported and the syntax for defining a conditional compilation symbol.

To define the "TRACE" conditional compilation symbol in C# and J#, add the /d:TRACE option 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 option to the compiler command line or add #Const TRACE=True to the file.

ConditionalAttribute is not supported by the C++ compiler. To provide equivalent functionality, you must enclose calls to the methods of Trace in an #if defined(TRACE) ... #endif block, and add the /DTRACE option to the compiler command line or add #define TRACE to the file.

In Visual Studio 2005 projects, by default, the "DEBUG" conditional compilation symbol is defined for debug builds, and the "TRACE" symbol is defined for both debug and release builds. For information on how to disable this behavior, see the Visual Studio 2005 documentation.

Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows CE Platform Note:

The .NET Compact Framework does not support tracing features that use a configuration file.

The following example uses Trace to indicate the beginning and the end of a program's execution. The example also uses Indent and Unindent to distinguish the tracing output.

' Specify /d:TRACE=True when compiling.

Imports System
Imports System.Diagnostics

Class Test

    Shared Sub Main()

        Trace.Listeners.Add(New TextWriterTraceListener(Console.Out))
        Trace.AutoFlush = True
        Trace.Indent()
        Trace.WriteLine("Entering Main")
        Console.WriteLine("Hello World.")
        Trace.WriteLine("Exiting Main")
        Trace.Unindent()

    End Sub 'Main

End Class

// Specify /d:TRACE when compiling.

using System;
using System.Diagnostics;

class Test
{
    static void Main()
    {
       Trace.Listeners.Add(new TextWriterTraceListener(Console.Out));
       Trace.AutoFlush = true;
       Trace.Indent();
       Trace.WriteLine("Entering Main");
       Console.WriteLine("Hello World.");
       Trace.WriteLine("Exiting Main"); 
       Trace.Unindent();
    }
}

// Specify /DTRACE when compiling.

#using <System.dll>
using namespace System;
using namespace System::Diagnostics;

int main()
{
   #if defined(TRACE)
   Trace::Listeners->Add( gcnew TextWriterTraceListener( Console::Out ) );
   Trace::AutoFlush = true;
   Trace::Indent();
   Trace::WriteLine( "Entering Main" );
   #endif
   Console::WriteLine( "Hello World." );
   #if defined(TRACE)
   Trace::WriteLine( "Exiting Main" );
   Trace::Unindent();
   #endif
   return 0;
}

• SecurityPermission 

  for operating with unmanaged code. Security action: Demand. Associated enumeration: SecurityPermissionFlag..::.UnmanagedCode

This type is thread safe.

Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360

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

.NET Framework

.NET Compact Framework

XNA Framework

Reference