Debug.WriteIf Method (Boolean, String, String)
Writes a category name and message to the trace listeners in the Listeners collection if a condition is true.
Assembly: System (in System.dll)
[<ConditionalAttribute("DEBUG")>] static member WriteIf : condition:bool * message:string * category:string -> unit
The conditional expression to evaluate. If the condition is true, the category name and message are written to the trace listeners in the collection.
A message to write.
A category name used to organize the output.
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.
if(mySwitch.TraceError) Debug.Write("aNumber = " + aNumber + " out of range");
Debug.WriteIf(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 TraceLevelVerbose, 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 Error or higher, the example outputs the second error message on the same line as the first message. A line terminator follows the second message.
Available since 10
Available since 1.1