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Debug.Fail Method (String)

Emits the specified error message.

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

[ConditionalAttribute("DEBUG")] 
public static void Fail (
	string message
)
/** @attribute ConditionalAttribute("DEBUG") */ 
public static void Fail (
	String message
)
ConditionalAttribute("DEBUG") 
public static function Fail (
	message : String
)
Not applicable.

Parameters

message

A message to emit.

The default behavior is that the DefaultTraceListener outputs the message to a message box when the application is running in user-interface mode and to the TraceListener instances in the Listeners collection.

NoteNote:

The display of the message box is dependent on the presence of the DefaultTraceListener. If the DefaultTraceListener is not in the Listeners collection, the message box is not displayed. The DefaultTraceListener can be removed by the <clear> Element for <listeners> for <trace>, the <remove> Element for <listeners> for <trace>, or by calling the Clear method on the Listeners property (System.Diagnostics.Trace.Listeners.Clear()).

You can customize this behavior by adding a TraceListener to, or removing one from, the Listeners collection.

The following example uses the Fail method to print a message during exception handling.

catch (Exception) {
    Debug.Fail("Unknown Option " + option + ", using the default.");
 }

catch (System.Exception exp) {
    Debug.Fail("Unknown Option " + option + ", using the default.");
}

catch (ex : Exception) {
    @if(@DEBUG)
    Debug.Fail("Cannot find SpecialController.");
    @end
    
    value = newValue;
 }

You can also use the Fail method in a switch statement.

switch (option) {
    case Option.First:
       result = 1.0;
       break;
 
    // Insert additional cases.
 
    default:
       Debug.Fail("Unknown Option " + option);
       result = 1.0;
       break;
 }

switch (option) {
    case Option.first :
        result = 1.0;
        break;

    // Insert additional cases.

    default :
        Debug.Fail("Unknown Option " + option);
        result = 1.0;
        break;
}

switch (option) {
    case MyOption.First:
       result = 1.0;
       break;
 
    // Insert additional cases.
 
    default:
       @if(@DEBUG)
       Debug.Fail("Unknown Option " + option);
       @end
       
       result = 1.0;
       break;
 }

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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