Retrieving Active Directory time fields with .net c#

I an working on an Intranet where I need to produce reports from Active Directory. I have no problem accessing and retrieving the AD data I need but have a problem converting lastLogon  to a real date/time. Apparently this is stored as a high part and a low part so needs HighPart and LowPart methods to break the number into two 32-bit components. I am going round in circles trying to find out how to do this in c#. Does anyone there have code that works ?
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Bob LearnedCommented:
This works for me, since I only have on DC.  If you have multiple DCs you will have to query each DC.

Add Reference to System.DirectoryServices + COM Active DS Type Library.

using System.DirectoryServices;
using ActiveDs;

      public string LastUserLogin()

         DirectorySearcher mySearch;
         SearchResult myResult;

         mySearch = new DirectorySearcher("cn=<User name goes here>");

         myResult = mySearch.FindOne();

         DirectoryEntry myEntry = new DirectoryEntry(myResult.Path);

         IADsLargeInteger li = (IADsLargeInteger) myEntry.Properties["lastLogon"][0];

         long fileDate = li.HighPart * 4294967296 + li.LowPart;
         string returnDate = DateTime.FromFileTime(fileDate).ToString() ;

         return returnDate;


This was an interesting challenge since I don't use C# very much.  

For those who care, here is the VB.NET code that I started with:

      Dim mySearch As New DirectorySearcher("cn=<User name goes here>")
      Dim myResult As SearchResult = mySearch.FindOne

      Dim myEntry As DirectoryEntry = New DirectoryEntry(myResult.Path)
      Dim fileDate As Long

      fileDate = (myEntry.Properties("lastLogon").Item(0).HighPart * 4294967296) + _

      Return DateTime.FromFileTime(fileDate).ToString
Bob LearnedCommented:
I know that you need it for C#, but I found this for VBScript:

Recipe 6.27: Determining a User's Last Logon Time

' This code prints the last logon timestamp for a user.
strUserDN = "<UserDN>"  ' e.g. cn=user,ou=department,dc=server,dc=com
' ------ END CONFIGURATION ---------
set objUser =  GetObject("LDAP://" & strUserDN)
set objLogon = objUser.Get("lastLogonTimestamp")
intLogonTime = objLogon.HighPart * (2^32) + objLogon.LowPart
intLogonTime = intLogonTime / (60 * 10000000)
intLogonTime = intLogonTime / 1440
WScript.Echo "Approx last logon timestamp: " & intLogonTime + #1/1/1601#
jegregoryAuthor Commented:
Thanks, I'd found that one but I can't tranlate it into c# ! The problem is I can't find a c# class that will do a high part, low part split.
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jegregoryAuthor Commented:
When I compile this I get 'The type or namespace ActiveDS could not be found'. I think this is because ActiveDS is not part of the .net framework, but part of ADSI. So how do I link in the ADSI bit - is there a dll I need ?

I am building this as part of an Intranet, so using web forms not Windows forms and accessing Active directory remotely from within the browser.

(I am using Dreamweaver for editing and the command line compiler -  not Visual Studio)

Bob LearnedCommented:
I have this in my .csproj file in the References section:

                    Name = "ActiveDs"
                    Guid = "{97D25DB0-0363-11CF-ABC4-02608C9E7553}"
                    VersionMajor = "1"
                    VersionMinor = "0"
                    Lcid = "0"
                    WrapperTool = "tlbimp"

Bob LearnedCommented:
No comment has been added lately, so it's time to clean up this TA.
I will leave the following recommendation for this question in the Cleanup topic area:

Accept: TheLearnedOne {http:#9874939}

Please leave any comments here within the next seven days.

EE Cleanup Volunteer
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