Solved

Doesn't Work in Delphi

Posted on 2001-06-13
9
231 Views
Last Modified: 2010-04-06
Can anyone tell me why this snippet of code works in VB but not in Delphi??

It's a Winpopup message sender.  If you use the function in VB then it sends the message fine.  In Delphi it doesn't send the message.

VB Code
-------

Const MAILSLOT_WAIT_FOREVER = (-1)
Const OPEN_EXISTING = 3
Const GENERIC_READ = &H80000000
Const GENERIC_WRITE = &H40000000
Const GENERIC_EXECUTE = &H20000000
Const GENERIC_ALL = &H10000000
Const INVALID_HANDLE_VALUE = -1
Const FILE_SHARE_READ = &H1
Const FILE_SHARE_WRITE = &H2
Const FILE_ATTRIBUTE_NORMAL = &H80
Private Declare Function CloseHandle Lib "kernel32" (ByVal hHandle As Long) As Long
Private Declare Function WriteFile Lib "kernel32" (ByVal hFileName As Long, ByVal lpBuff As Any, ByVal nNrBytesToWrite As Long, lpNrOfBytesWritten As Long, ByVal lpOverlapped As Long) As Long
Private Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" (ByVal lpFileName As String, ByVal dwAccess As Long, ByVal dwShare As Long, ByVal lpSecurityAttrib As Long, ByVal dwCreationDisp As Long, ByVal dwAttributes As Long, ByVal hTemplateFile As Long) As Long


Function SendMsg(From1 As String, To2 As String, Text3 As String) As Long
Dim rc As Long
Dim mshandle As Long
Dim msgtxt As String
Dim byteswritten As Long
Dim mailslotname As String
' name of the mailslot
    mailslotname = "\\" + To2 + "\mailslot\messngr"
    msgtxt = From1 + Chr(0) + To2 + Chr(0) + Text3 + Chr(0)
    mshandle = CreateFile(mailslotname, GENERIC_WRITE, FILE_SHARE_READ, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, -1)
    rc = WriteFile(mshandle, msgtxt, Len(msgtxt), byteswritten, 0)
    rc = CloseHandle(mshandle)
End Function



Delphi Code
-----------

procedure TForm1.SendNetMessage(YourName, ComputerName,
  MessageStr: String);
Var
   Rc : LongBool;
   MsHandle : Longint;
   MsgText : String;
   BytesWritten : Cardinal;
   MailSlotName : String;
begin
    // Name of the mailslot
    MailSlotName := '\\' + ComputerName + '\mailslot\messngr';
    MsgText := YourName + Chr(0) + ComputerName + Chr(0) + MessageStr + Chr(0);
    MsHandle := CreateFile(PChar(MailSlotName), GENERIC_WRITE, FILE_SHARE_READ, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
    Rc := WriteFile(MsHandle, MsgText, Length(MsgText), BytesWritten, 0);
    Rc := CloseHandle(MsHandle);
end;



Can anyone fix it or tell me where I went wrong??

Cheers
Woody.
0
Comment
Question by:WoodyJ007
  • 4
  • 4
9 Comments
 
LVL 8

Expert Comment

by:TOndrej
ID: 6186752
Hi Woody,
is MsHandle returned from CreateFile valid or is it INVALID_HANDLE_VALUE?

perhaps you could write it in this way:

MsHandle := CreateFile(...);
if MsHandle = INVALID_HANDLE_VALUE then
  RaiseLastWin32Error;
try
  Rc := WriteFile(...);
  if not Rc then
    RaiseLastWin32Error;
finally
  Rc := CloseHandle(MsHandle);
end;

so you can see an error message if something goes wrong...
0
 

Author Comment

by:WoodyJ007
ID: 6186871
The handle is fine.  

If you have VB or Delphi installed, and your on a network as well. try it out.

The only difference I did was using 0 instead of -1 in the last param of create file.
0
 
LVL 8

Expert Comment

by:TOndrej
ID: 6186910
oops... ;-)
Does it work now?

I wish we could write sections marked as <CODE> (rendered in a non-proportional font) so the code posted here is more readable...
0
 

Author Comment

by:WoodyJ007
ID: 6186964
No it still doesn't work.  You can't put -1 as the last param because it is cardinal.
0
Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

 
LVL 8

Expert Comment

by:TOndrej
ID: 6186974
just typecast:

Cardinal(-1)

that will compile.
0
 

Author Comment

by:WoodyJ007
ID: 6187141
that didn't work either,still doesn't work under delphi.
0
 
LVL 8

Expert Comment

by:TOndrej
ID: 6187151
Define "doesn't work"... Does the code compile? If it does, it's time to put in the error checking lines I posted earlier ;-)
0
 
LVL 26

Accepted Solution

by:
Russell Libby earned 50 total points
ID: 6188097
Woody,

With the understanding that you have a valid handle (from what I can tell from above), the problem lies in the WriteFile().

Switch to:

WriteFile(MsHandle, Pointer(MsgText)^, Length(MsgText), BytesWritten, 0);
   
0
 

Author Comment

by:WoodyJ007
ID: 6190008
Yeah, that works great.  For some reason I thought I was supposed to be putting the string in instead of a pointer to it.

Thanks to everyone else for the help.

Cheers
Woody.
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
How to disable drag and drop of columns in a TVirtualStringTree 3 72
IExtractImage Delphi 14 201
Sending Gmail through Delphi 3 91
How to renew a Delphi rad-studio licence? 5 49
In this tutorial I will show you how to use the Windows Speech API in Delphi. I will only cover basic functions such as text to speech and controlling the speed of the speech. SAPI Installation First you need to install the SAPI type library, th…
Have you ever had your Delphi form/application just hanging while waiting for data to load? This is the article to read if you want to learn some things about adding threads for data loading in the background. First, I'll setup a general applica…
This Micro Tutorial hows how you can integrate  Mac OSX to a Windows Active Directory Domain. Apple has made it easy to allow users to bind their macs to a windows domain with relative ease. The following video show how to bind OSX Mavericks to …
Windows 10 is mostly good. However the one thing that annoys me is how many clicks you have to do to dial a VPN connection. You have to go to settings from the start menu, (2 clicks), Network and Internet (1 click), Click VPN (another click) then fi…

911 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

16 Experts available now in Live!

Get 1:1 Help Now