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Debug.WriteLineIf Method (Boolean, String, String)

Writes a category name and message to the trace listeners in the Listeners collection if a condition is true.

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

[ConditionalAttribute("DEBUG")] 
public static void WriteLineIf (
	bool condition,
	string message,
	string category
)
/** @attribute ConditionalAttribute("DEBUG") */ 
public static void WriteLineIf (
	boolean condition, 
	String message, 
	String category
)
ConditionalAttribute("DEBUG") 
public static function WriteLineIf (
	condition : boolean, 
	message : String, 
	category : String
)
Not applicable.

Parameters

condition

true to cause a message to be written; otherwise, false.

message

A message to write.

category

A category name used to organize the output.

By default, the output is written to an instance of DefaultTraceListener.

The category parameter can be used to group output messages.

This method calls the WriteLine method of the trace listener.

Notes to Implementers: You can minimize the performance penalty of instrumenting your application by using If...Then statements instead of using WriteLineIf statements. The following two code examples send the same debugging message. However, the first example is much faster when tracing is off, because if mySwitch.TraceError evaluates to false, you do not call WriteLine. The second example always calls WriteLineIf, even when mySwitch.TraceError is false and no tracing output is produced. This can result in unnecessary execution of arbitrarily complex code. First example.

 if(mySwitch.TraceError) 
     Debug.WriteLine("aNumber = " + aNumber + " out of range");
Second example.
 Debug.WriteLineIf(mySwitch.TraceError, "aNumber = " + aNumber + " out of range");

The following example creates a TraceSwitch named generalSwitch. This switch is set outside of the code sample.

If the switch is set to the TraceLevelError or higher, the example outputs the first error message to the Listeners. For information on adding a listener to the Listeners collection, see the TraceListenerCollection class.

Then, if the TraceLevel is set to Verbose, the example outputs the second error message and the category on the same line as the first message. A line terminator follows the second message.

// Class-level declaration.
 // Create a TraceSwitch.
 static TraceSwitch generalSwitch = new TraceSwitch("General", "Entire Application");
 
 static public void MyErrorMethod(String category) {
    // Write the message if the TraceSwitch level is set to Error or higher.
    Debug.WriteIf(generalSwitch.TraceError, "My error message. ");
 
    // Write a second message if the TraceSwitch level is set to Verbose.
    Debug.WriteLineIf(generalSwitch.TraceVerbose, "My second error message.", category);
 }


// Class-level declaration.
// Create a TraceSwitch.
private static TraceSwitch generalSwitch = 
    new TraceSwitch("General", "Entire Application");

public static void MyErrorMethod(String category)
{
    // Write the message if the TraceSwitch level is set to Error 
    // or higher.
    Debug.WriteIf(generalSwitch.get_TraceError(), "My error message. ");

    // Write a second message if the TraceSwitch level is set to Verbose.
    Debug.WriteLineIf(generalSwitch.get_TraceVerbose(), 
        "My second error message.", category);
} //MyErrorMethod

// Create a TraceSwitch.
static var generalSwitch : TraceSwitch = 
   new TraceSwitch("General", "Entire Application")    

static public function MyErrorMethod(category : String)
{
   @if(@DEBUG)
   // Write the message if the TraceSwitch level is set to
   // Error or higher.
   Debug.WriteIf(generalSwitch.TraceError, "My error message. ");

   // Write a second message if the TraceSwitch level 
   // is set to Verbose.
   Debug.WriteLineIf(generalSwitch.TraceVerbose, "My second error message.", category);
   @end
}

Windows 98, Windows Server 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 Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0
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