TraceSwitch Class


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Provides a multilevel switch to control tracing and debug output without recompiling your code.

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


public ref class TraceSwitch : Switch

System_CAPS_pubmethodTraceSwitch(String^, String^)

Initializes a new instance of the TraceSwitch class, using the specified display name and description.

System_CAPS_pubmethodTraceSwitch(String^, String^, String^)

Initializes a new instance of the TraceSwitch class, using the specified display name, description, and default value for the switch.


Gets the custom switch attributes defined in the application configuration file.(Inherited from Switch.)


Gets a description of the switch.(Inherited from Switch.)


Gets a name used to identify the switch.(Inherited from Switch.)


Gets or sets the trace level that determines the messages the switch allows.


Gets or sets the current setting for this switch.(Inherited from Switch.)


Gets a value indicating whether the switch allows error-handling messages.


Gets a value indicating whether the switch allows informational messages.


Gets a value indicating whether the switch allows all messages.


Gets a value indicating whether the switch allows warning messages.


Gets or sets the value of the switch.(Inherited from Switch.)


Determines whether the specified object is equal to the current object.(Inherited from Object.)


Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)


Serves as the default hash function. (Inherited from Object.)


Gets the custom attributes supported by the switch.(Inherited from Switch.)


Gets the Type of the current instance.(Inherited from Object.)


Creates a shallow copy of the current Object.(Inherited from Object.)


Updates and corrects the level for this switch.(Overrides Switch::OnSwitchSettingChanged().)


Sets the SwitchSetting property to the integer equivalent of the Value property.(Overrides Switch::OnValueChanged().)


Returns a string that represents the current object.(Inherited from Object.)

You can use a trace switch to filter out messages based on their importance. The TraceSwitch class provides the TraceError, TraceWarning, TraceInfo, and TraceVerbose properties to test the level of the switch. The Level property gets or sets the switch's TraceLevel.

You can set the level of a TraceSwitch through the application configuration file and then use the configured TraceSwitch level in your application. Alternately, you can create a TraceSwitch in your code and set the level directly to instrument a specific section of code.

To configure a TraceSwitch, edit the for your application. In this file, you can add or remove a switch, set a switch's value, or clear all the switches previously set by the application. The configuration file should be formatted like the following example:

      <add name="mySwitch" value="1" />

This configuration section defines a TraceSwitch with the DisplayName set to mySwitch, and the Level set to 1, which corresponds to the enumeration value TraceLevel::Error.


In the .NET Framework version 2.0, you can use text to specify the value for a switch. For example, true for a BooleanSwitch or the text representing an enumeration value, such as Error for a TraceSwitch. The line <add name="mySwitch" value="Error" /> is equivalent to <add name="mySwitch" value="1" />.

In your application, you can use the configured switch level by creating a TraceSwitch with the same name, as shown in the following example:

    static TraceSwitch^ appSwitch = gcnew TraceSwitch("mySwitch",
        "Switch in config file");

    static void Main(array<String^>^ args)
        Console::WriteLine("Trace switch {0} configured as {1}",
        appSwitch->DisplayName, appSwitch->Level.ToString());
        if (appSwitch->TraceError)

By default, the switch Level property is set using the value specified in the configuration file. If the TraceSwitch constructor cannot find initial switch settings in the configuration file, the Level of the new switch defaults to TraceLevel::Off.

You must enable tracing or debugging to use a switch. 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 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.


These debug and trace compiler switches are not required when using the TraceSwitch class in isolation. They are only required in conjunction with Trace or Debug methods that are conditionally compiled.

For more information on instrumenting your application, see Debug and Trace. For more information about configuring and using trace switches, see Trace Switches.


To improve performance, you can make TraceSwitch members static in your class.

The following code example creates a new TraceSwitch and uses the switch to determine whether to print error messages. The switch is created at the class level. MyMethod writes the first error message if the Level property is set to TraceLevel::Error or higher. However, MyMethod does not write the second error message if the Level is less than TraceLevel::Verbose.

   // Class-level declaration.
   /* Create a TraceSwitch to use in the entire application.*/
   static TraceSwitch^ mySwitch = gcnew TraceSwitch( "General", "Entire Application" );

   static void MyMethod()
      // Write the message if the TraceSwitch level is set to Error or higher.
      if ( mySwitch->TraceError )
         Console::WriteLine( "My error message." );

      // Write the message if the TraceSwitch level is set to Verbose.
      if ( mySwitch->TraceVerbose )
         Console::WriteLine( "My second error message." );

   static void main()
      // Run the method that prints error messages based on the switch level.

.NET Framework
Available since 1.1

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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