Debug Class

Provides a set of methods and properties that help debug your code. This class cannot be inherited.

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

public sealed class Debug
public final class Debug
public final class Debug

If you use methods in the Debug class to print debugging information and check your logic with assertions, you can make your code more robust without impacting the performance and code size of your shipping product.

In Visual Studio 2005 projects, creating a debug build enables Debug. For information on how to disable Debug, see the Visual Studio 2005 documentation.

In contrast, in Visual Studio 2005 projects, Trace is enabled by default for both release and debug builds, so code is generated for all trace methods in both release and debug builds. Therefore, you can use Trace to instrument release builds.

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 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, the DefaultTraceListener class emits trace output.

You can modify the level of indentation using the Indent method or the IndentLevel property. To modify the indent spacing, use the IndentSize property. You can specify whether to automatically flush the output buffer after each write by setting the AutoFlush property to true.

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

        <trace autoflush="true" indentsize="7" />

To enable debugging in C#, add the /d:DEBUG flag to the compiler command line when you compile your code, or add #define DEBUG to the top of your file. In Visual Basic, add the /d:DEBUG=True flag to the compiler command line. To provide equivalent functionality in C++, you must enclose calls to methods of this class in a #ifdef DEBUG... #endif block. This syntax is compiler-specific. If you are using a compiler other than the ones specified above, you must refer to the compiler's documentation to enable conditional compiling because of the conditional compilation attributes placed on the methods of Debug.

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

static int Main(string[] args)
   Debug.Listeners.Add(new TextWriterTraceListener(Console.Out));
   Debug.AutoFlush = true;
   Debug.WriteLine("Entering Main");
   Console.WriteLine("Hello World.");
   Debug.WriteLine("Exiting Main"); 
   return 0;


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