EventLog.WriteEntry Method (String) (System.Diagnostics)

WriteEntry Method (String)

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Microsoft Visual Studio 2005/.NET Framework 2.0

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.NET Framework Class Library

EventLog.WriteEntry Method (String)

Writes an information type entry, with the given message text, to the event log.

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

Syntax

Visual Basic (Declaration)

Public Sub WriteEntry ( _
    message As String _
)

Visual Basic (Usage)

Dim instance As EventLog
Dim message As String

instance.WriteEntry(message)

public void WriteEntry (
    string message
)

C++

public:
void WriteEntry (
    String^ message
)

public void WriteEntry (
    String message
)

JScript

public function WriteEntry (
    message : String
)

Parameters

message: The string to write to the event log.

Exceptions

Exception type	Condition
ArgumentException	The Source property of the EventLog has not been set. -or- The method attempted to register a new event source, but the computer name in MachineName is not valid. - or - The source is already registered for a different event log. - or - The message string is longer than 32766 bytes. - or - The source name results in a registry key path longer than 254 characters.
InvalidOperationException	The registry key for the event log could not be opened.
Win32Exception	The operating system reported an error when writing the event entry to the event log. A Windows error code is not available.

Exception type

Condition

ArgumentException

The Source property of the EventLog has not been set.

-or-

The method attempted to register a new event source, but the computer name in MachineName is not valid.

- or -

The source is already registered for a different event log.

- or -

The message string is longer than 32766 bytes.

- or -

The source name results in a registry key path longer than 254 characters.

InvalidOperationException

The registry key for the event log could not be opened.

Win32Exception

The operating system reported an error when writing the event entry to the event log. A Windows error code is not available.

Remarks

Use this method to write an information entry to the event log associated with this EventLog instance. If you want to specify any other EventLogEntryType, use a different overload of WriteEntry.

You must set the Source property on your EventLog component before you can write entries to the log. You must create and configure the event source before writing the first entry with the source.

Create the new event source during the installation of your application. This allows time for the operating system to refresh its list of registered event sources and their configuration. If the operating system has not refreshed its list of event sources, and you attempt to write an event with the new source, the write operation will fail. You can configure a new source using an EventLogInstaller, or using the CreateEventSource method. You must have administrative rights on the computer to create a new event source.

If the source specified in the Source property of this EventLog instance is not registered on the computer that your component is writing to, WriteEntry calls CreateEventSource and registers the source.

Note
If you do not specify a MachineName for your EventLog instance before you call CreateEventSource or WriteEntry, the local computer (".") is assumed.

If the system needs to register the Source through a call to WriteEntry and the Log property has not been set on your EventLog instance, the log defaults to the Application log.

Note
Many of the exceptions listed above are generated by errors raised during the process of registering the Source.

The source must be configured either for writing localized entries or for writing direct strings. The WriteEntry method writes the given string directly to the event log; it does not use a localizable message resource file. Use the WriteEvent method to write events using a localized message resource file.

If your application writes entries using both resource identifiers and string values, you must register two separate sources. For example, configure one source with resource files, and then use that source in the WriteEvent method to write entries using resource identifiers to the event log. Then create a different source without resource files, and use that source in the WriteEntry method to write strings directly to the event log using that source.

Note
If you write an entry to a remote computer, the value of the message (the text string) might not be what you expect if the remote computer is not running the .NET Framework.

Note
If the message parameter contains a NUL character, the message in the event log is terminated at the NUL character.

Note

If the message parameter contains a NUL character, the message in the event log is terminated at the NUL character.

Example

The following example creates the source MySource if it does not already exist, and writes an entry to the event log MyNewLog.

Visual Basic

Option Explicit
Option Strict

Imports System
Imports System.Diagnostics
Imports System.Threading

Class MySample
    Public Shared Sub Main()
        
        ' Create the source, if it does not already exist.
        If Not EventLog.SourceExists("MySource") Then
            EventLog.CreateEventSource("MySource", "MyNewLog")
            Console.WriteLine("CreatingEventSource")
        End If
        
        ' Create an EventLog instance and assign its source.
        Dim myLog As New EventLog()
        myLog.Source = "MySource"
        
        ' Write an informational entry to the event log.    
        myLog.WriteEntry("Writing to event log.")
    End Sub 'Main 
End Class 'MySample

using System;
using System.Diagnostics;
using System.Threading;
              
class MySample{

    public static void Main(){
    
        // Create the source, if it does not already exist.
        if(!EventLog.SourceExists("MySource")){
            EventLog.CreateEventSource("MySource", "MyNewLog");
            Console.WriteLine("CreatingEventSource");
        }
                
        // Create an EventLog instance and assign its source.
        EventLog myLog = new EventLog();
        myLog.Source = "MySource";
        
        // Write an informational entry to the event log.    
        myLog.WriteEntry("Writing to event log.");
        
    }
}

C++

#using <System.dll>

using namespace System;
using namespace System::Diagnostics;
using namespace System::Threading;
int main()
{
   
   // Create the source, if it does not already exist.
   if (  !EventLog::SourceExists( "MySource" ) )
   {
      EventLog::CreateEventSource( "MySource", "MyNewLog" );
      Console::WriteLine( "CreatingEventSource" );
   }

   
   // Create an EventLog instance and assign its source.
   EventLog^ myLog = gcnew EventLog;
   myLog->Source = "MySource";
   
   // Write an informational entry to the event log.    
   myLog->WriteEntry( "Writing to event log." );
}

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

class MySample
{
    public static void main(String[] args)
    {
        // Create the source, if it does not already exist.
        if (!(EventLog.SourceExists("MySource"))) {
            EventLog.CreateEventSource("MySource", "MyNewLog");
            Console.WriteLine("CreatingEventSource");
        }

        // Create an EventLog instance and assign its source.
        EventLog myLog = new EventLog();
        myLog.set_Source("MySource");

        // Write an informational entry to the event log.    
        myLog.WriteEntry("Writing to event log.");
    } //main 
} //MySample

.NET Framework Security

EventLogPermission for writing the event log information on the computer. Associated enumeration: EventLogPermissionAccess.Write

Platforms

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.

Version Information

.NET Framework

Supported in: 2.0, 1.1, 1.0

Reference

EventLog Class
EventLog Members
System.Diagnostics Namespace
Source
CreateEventSource
DeleteEventSource
SourceExists
Entries