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EventLog Constructor (String, String, String)

Initializes a new instance of the EventLog class. Associates the instance with a log on the specified computer and creates or assigns the specified source to the EventLog.

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

EventLog (
	String^ logName, 
	String^ machineName, 
	String^ source
public EventLog (
	String logName, 
	String machineName, 
	String source
public function EventLog (
	logName : String, 
	machineName : String, 
	source : String



The name of the log on the specified computer


The computer on which the log exists.


The source of event log entries.

Exception typeCondition


The log name is a null reference (Nothing in Visual Basic).


The log name is invalid.


The computer name is invalid.

This constructor sets the Log property to the logName parameter, the MachineName property to the machineName parameter, and the Source property to the source parameter. The Source property is required when writing to an event log. However, if you are only reading from an event log, only the Log and MachineName properties are required (as long as the event log on the server has a source already associated with it). If you are only reading from the event log, another overload of the constructor might suffice.

The following table shows initial property values for an instance of EventLog.


Initial Value


The source parameter.


The logName parameter.


The machineName parameter.

The following example writes an entry to an event log, "MyNewLog", on the local computer, using the source "MySource".

#using <System.dll>

using namespace System;
using namespace System::Diagnostics;
using namespace System::Threading;
int main()
   // Create an EventLog instance and assign its source.
   EventLog^ myLog = gcnew EventLog( "myNewLog",".","MySource" );
   // Write an entry to the log.        
   myLog->WriteEntry( String::Format( "Writing to event log on {0}", myLog->MachineName ) );

import System.*;
import System.Diagnostics.*;
import System.Threading.*;

class MySample
    public static void main(String[] args)
        // Create an EventLog instance and assign its source.
        EventLog myLog = new EventLog("myNewLog", ".", "MySource");
        // Write an entry to the log.        
        myLog.WriteEntry("Writing to event log on " 
            + myLog.get_MachineName());
    } //main 
} //MySample

Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0