EventLog.Exists Method

Definition

Namespace:

System.Diagnostics

Assembly:

System.Diagnostics.EventLog.dll

Determines whether the specified log exists.

Overloads

Exists(String)	Determines whether the log exists on the local computer.
Exists(String, String)	Determines whether the log exists on the specified computer.

Exists(String)

Source:

EventLog.cs

Determines whether the log exists on the local computer.

public:
 static bool Exists(System::String ^ logName);

public static bool Exists (string logName);

static member Exists : string -> bool

Public Shared Function Exists (logName As String) As Boolean

Parameters

logName

String

The name of the log to search for. Possible values include: Application, Security, System, other application-specific logs (such as those associated with Active Directory), or any custom log on the computer.

Returns

Boolean

true if the log exists on the local computer; otherwise, false.

Exceptions

ArgumentException

The logName is null or the value is empty.

Examples

      String^ myLog = "myNewLog";
      if ( EventLog::Exists( myLog ) )
      {
         Console::WriteLine( "Log '{0}' exists.", myLog );
      }
      else
      {
         Console::WriteLine( "Log '{0}' does not exist.", myLog );
      }
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "Exception: {0}", e->Message );
   }

}

string myLog = "myNewLog";
if (EventLog.Exists(myLog))
{
   Console.WriteLine("Log '"+myLog+"' exists.");
}
else
{
   Console.WriteLine("Log '"+myLog+"' does not exist.");
}

Dim myLog As String = "myNewLog"
If EventLog.Exists(myLog) Then
   Console.WriteLine("Log '" + myLog + "' exists.")
Else
   Console.WriteLine("Log '" + myLog + "' does not exist.")
End If

Remarks

Use this method to determine if a log exists on the local computer. If you want to determine whether a source exists on the local computer, use SourceExists.

Because this method accesses the registry, you must have the appropriate registry permissions on the local computer; otherwise, the query returns false.

Because you cannot give a new log the name of an existing log on the same computer, use this method before creating a new log to determine if the specified logName already exists on the local computer. The logName parameter is not case sensitive.

Exists is a static method, so it can be called on the class itself. It is not necessary to create an instance of EventLog to call Exists.

See also

• CreateEventSource
• Delete(String)
• SourceExists(String)
• Log

Exists(String, String)

Source:

EventLog.cs

Determines whether the log exists on the specified computer.

public:
 static bool Exists(System::String ^ logName, System::String ^ machineName);

public static bool Exists (string logName, string machineName);

static member Exists : string * string -> bool

Public Shared Function Exists (logName As String, machineName As String) As Boolean

Parameters

logName

String

The log for which to search. Possible values include: Application, Security, System, other application-specific logs (such as those associated with Active Directory), or any custom log on the computer.

machineName

String

The name of the computer on which to search for the log, or "." for the local computer.

Returns

Boolean

true if the log exists on the specified computer; otherwise, false.

Exceptions

ArgumentException

The machineName parameter is an invalid format. Make sure you have used proper syntax for the computer on which you are searching.

-or-

The logName is null or the value is empty.

Remarks

Use this method to determine if a log exists on a remote computer. If you want to determine whether a source exists on a remote computer, use SourceExists.

Because this method accesses the registry, you must have the appropriate registry permissions on the specified computer; otherwise, the query returns false.

Because you cannot give a new log the name of an existing log on the same computer, use this method before creating a new log to determine if one with the specified logName already exists on the server specified by the machineName parameter. The logName and machineName parameters are not case sensitive.

Exists is a static method, so it can be called on the class itself. It is not necessary to create a new instance of EventLog to call Exists.

See also

• CreateEventSource
• Delete(String)
• SourceExists(String)
• Log
• MachineName