This documentation is archived and is not being maintained.

Debug.WriteIf Method (Boolean, String)

.NET Framework 1.1

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

[Visual Basic]
<Conditional("DEBUG")>
Overloads Public Shared Sub WriteIf( _
   ByVal condition As Boolean, _
   ByVal message As String _
)
[C#]
[Conditional("DEBUG")]
public static void WriteIf(
 bool condition,
 string message
);
[C++]
[Conditional("DEBUG")]
public: static void WriteIf(
 bool condition,
 String* message
);
[JScript]
public
   Conditional("DEBUG")
static function WriteIf(
 condition : Boolean,
 message : String
);

Parameters

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

Remarks

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

This method calls the Write 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 WriteIf 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 Write. The second example always calls WriteIf, 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.Write("aNumber = " + aNumber + " out of range");

Second example.

Debug.WriteIf(mySwitch.TraceError, "aNumber = " + aNumber + " out of range");

Example

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

If the switch is set to the TraceLevel Error 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 on the same line as the first message. A line terminator follows the second message.

[Visual Basic] 
' Class-level declaration.
' Create a TraceSwitch.
Private Shared generalSwitch As New TraceSwitch("General", "Entire Application")


Public Shared Sub MyErrorMethod()
    ' 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.WriteIf(generalSwitch.TraceVerbose, "My second error message.")
End Sub 'MyErrorMethod

[C#] 
// Class-level declaration.
 // Create a TraceSwitch.
 static TraceSwitch generalSwitch = new TraceSwitch("General", "Entire Application");
 
 static public void MyErrorMethod() {
    // 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.WriteIf(generalSwitch.TraceVerbose, "My second error message.");
 }


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


[JScript] 
// Class level declaration.
 // Create a TraceSwitch.
 static var generalSwitch : TraceSwitch = new TraceSwitch("General", "Entire Application");
 
 static public function MyErrorMethod() {
    // 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.WriteIf(generalSwitch.TraceVerbose, "My second error message.");
 }

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

See Also

Debug Class | Debug Members | System.Diagnostics Namespace | Debug.WriteIf Overload List | Debug | Trace | BooleanSwitch | TraceSwitch | TraceListener | DefaultTraceListener | ConditionalAttribute | ConditionalAttribute | ConditionalAttribute | ConditionalAttribute | ConditionalAttribute

Show: