Debug Class

Definition

Namespace:

System.Diagnostics

Assembly:

System.Runtime.dll

Source:

Debug.cs

Provides a set of methods and properties that help debug your code.

public ref class Debug abstract sealed

public static class Debug

type Debug = class

Public Class Debug

Inheritance

Object

Debug

Examples

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.

// Specify /DDEBUG when compiling.

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

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

// Specify /d:DEBUG when compiling.

using System;
using System.Data;
using System.Diagnostics;

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

' Specify /d:DEBUG=True when compiling.

Imports System.Data
Imports System.Diagnostics

Class Test

    Shared Sub Main()
    
        Debug.Listeners.Add(New TextWriterTraceListener(Console.Out))
        Debug.AutoFlush = True
        Debug.Indent()
        Debug.WriteLine("Entering Main")
        Console.WriteLine("Hello World.")
        Debug.WriteLine("Exiting Main")
        Debug.Unindent()
        
    End Sub
    
End Class

Remarks

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

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
• WriteLineIf

The BooleanSwitch and TraceSwitch classes provide means to dynamically control the tracing output. For .NET Framework apps, you can modify the values of these switches without recompiling your application. For information on using the configuration file to set a switch in .NET Framework apps, see the Switch class and the Trace Switches article.

You can customize the tracing output's target by adding TraceListener instances to or removing instances from the Listeners collection. The Listeners collection is shared by both the Debug and the Trace classes; adding a trace listener to either class adds the listener to both. By default, the DefaultTraceListener class emits trace output.

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 can't be enumerated in this article. It may be useful to place calls to the Debug methods in try/catch blocks to detect and handle any exceptions from trace listeners.

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.

For .NET Framework apps, you can set the AutoFlush and IndentSize for Debug by editing your app's configuration file. The configuration file should be formatted as shown in the following example.

<configuration>
  <system.diagnostics>
    <trace autoflush="true" indentsize="7" />
  </system.diagnostics>
</configuration>

The ConditionalAttribute attribute is applied to the methods of Debug. Compilers that support ConditionalAttribute ignore calls to these methods unless DEBUG 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.

Note

In Visual Studio C# and Visual Basic 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 about conditional debugging in Visual C++, see Debug class (C++/CLI).

To define the DEBUG conditional compilation symbol in C#, add the /d:DEBUG option to the compiler command line when you compile your code using a command line, or add #define DEBUG to the top of your file. In Visual Basic, add the /d:DEBUG=True option to the compiler command line or add #Const DEBUG=True to the file.

Properties

AutoFlush	Gets or sets a value indicating whether Flush() should be called on the Listeners after every write.
IndentLevel	Gets or sets the indent level.
IndentSize	Gets or sets the number of spaces in an indent.

Methods

Assert(Boolean)	Checks for a condition; if the condition is false, displays a message box that shows the call stack.
Assert(Boolean, Debug+AssertInterpolatedStringHandler)	Checks for a condition; if the condition is false, outputs a specified message and displays a message box that shows the call stack.
Assert(Boolean, Debug+AssertInterpolatedStringHandler, Debug+AssertInterpolatedStringHandler)	Checks for a condition; if the condition is false, outputs a specified message and displays a message box that shows the call stack.
Assert(Boolean, String)	Checks for a condition; if the condition is false, outputs a specified message and displays a message box that shows the call stack.
Assert(Boolean, String, String)	Checks for a condition; if the condition is false, outputs two specified messages and displays a message box that shows the call stack.
Assert(Boolean, String, String, Object[])	Checks for a condition; if the condition is false, outputs two messages (simple and formatted) and displays a message box that shows the call stack.
Close()	Flushes the output buffer and then calls the Close method on each of the Listeners.
Fail(String)	Emits the specified error message.
Fail(String, String)	Emits an error message and a detailed error message.
Flush()	Flushes the output buffer and causes buffered data to write to the Listeners collection.
Indent()	Increases the current IndentLevel by one.
Print(String)	Writes a message followed by a line terminator to the trace listeners in the Listeners collection.
Print(String, Object[])	Writes a formatted string followed by a line terminator to the trace listeners in the Listeners collection.
Unindent()	Decreases the current IndentLevel by one.
Write(Object)	Writes the value of the object's ToString() method to the trace listeners in the Listeners collection.
Write(Object, String)	Writes a category name and the value of the object's ToString() method to the trace listeners in the Listeners collection.
Write(String)	Writes a message to the trace listeners in the Listeners collection.
Write(String, String)	Writes a category name and message to the trace listeners in the Listeners collection.
WriteIf(Boolean, Debug+WriteIfInterpolatedStringHandler)	If condition is true, writes a category name and message to the trace listeners in the Listeners collection.
WriteIf(Boolean, Debug+WriteIfInterpolatedStringHandler, String)	Writes a category name and message to the trace listeners in the Listeners collection if a specified condition is true.
WriteIf(Boolean, Object)	Writes the value of the object's ToString() method to the trace listeners in the Listeners collection if a condition is true.
WriteIf(Boolean, Object, String)	Writes a category name and the value of the object's ToString() method to the trace listeners in the Listeners collection if a condition is true.
WriteIf(Boolean, String)	Writes a message to the trace listeners in the Listeners collection if a condition is true.
WriteIf(Boolean, String, String)	Writes a category name and message to the trace listeners in the Listeners collection if a condition is true.
WriteLine(Object)	Writes the value of the object's ToString() method to the trace listeners in the Listeners collection.
WriteLine(Object, String)	Writes a category name and the value of the object's ToString() method to the trace listeners in the Listeners collection.
WriteLine(String)	Writes a message followed by a line terminator to the trace listeners in the Listeners collection.
WriteLine(String, Object[])	Writes a formatted message followed by a line terminator to the trace listeners in the Listeners collection.
WriteLine(String, String)	Writes a category name and message to the trace listeners in the Listeners collection.
WriteLineIf(Boolean, Debug+WriteIfInterpolatedStringHandler)	Writes a message to the trace listeners in the Listeners collection if a specified condition is true.
WriteLineIf(Boolean, Debug+WriteIfInterpolatedStringHandler, String)	Writes a category name and message to the trace listeners in the Listeners collection if a specified condition is true.
WriteLineIf(Boolean, Object)	Writes the value of the object's ToString() method to the trace listeners in the Listeners collection if a condition is true.
WriteLineIf(Boolean, Object, String)	Writes a category name and the value of the object's ToString() method to the trace listeners in the Listeners collection if a condition is true.
WriteLineIf(Boolean, String)	Writes a message to the trace listeners in the Listeners collection if a condition is true.
WriteLineIf(Boolean, String, String)	Writes a category name and message to the trace listeners in the Listeners collection if a condition is true.

Thread Safety

This type is thread safe.

See also

• Trace
• Switch
• BooleanSwitch
• TraceSwitch
• TraceListener
• DefaultTraceListener
• ConsoleTraceListener
• EventLogTraceListener
• TraceListenerCollection
• ConditionalAttribute