Solved

pointers, OLEVariant, Arrays of OLEVariant

Posted on 2001-09-13
4
1,439 Views
Last Modified: 2011-10-03
Can anybody point me to any documents which clearly explains how to use pointers with OLEVariant and Arrays of OLEVariant. I am being passed parameters of these types from a Server and need to extract the data that is being passed to my program. I am finding it all very confusing.

Thanks.
0
Comment
Question by:JohnMcGill
4 Comments
 
LVL 9

Accepted Solution

by:
ITugay earned 100 total points
ID: 6479481
Hi JohnMcGill,

you can use typecasting to convert pointer to integer and back.

var
  V: OLEVariant;
  T: TEdit;

begin
  V := Integer(Edit1);

  TEdit(Integer(V)).Text := 'some text';
end;

----
Igor.
0
 
LVL 14

Assisted Solution

by:AvonWyss
AvonWyss earned 100 total points
ID: 6479560
Arrays passed along in OLE automation are often pointers to so-called safe arrays (PSafeArray). These are arrays of OLE-compatible variants (OLEVariant). If you get a pointer to a safe array, you can quickly convert it to a OLEVariant array and vice-versa:

function SafeArrayToVariant(SaveArray: PSafeArray): OleVariant;
begin
    TVarData(Result).VType:=varArray;
    TVarData(Result).VArray:=PVarArray(SaveArray);
end;

The other way around goes like this:

function VariantToSafeArray(const Arr: OleVariant): PSafeArray;
begin
   Assert(TVarData(Arr).VType=varArray);
   Result:=PSafeArray(TVarData(Arr).VArray);
end;

[...]
var
    Strings: OleVariant;
    Temp: PSafeArray;
[...]
    {I assume that Temp holds the PSafeArray)
    Strings:=SafeArrayToVariant(Temp);  

And when it is in the Variant, you can just use it like a normal Pascal array...:

   Edit1.Text:=Strings[0];  

Hope this helps!
0
 
LVL 17

Expert Comment

by:geobul
ID: 9307969
No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:

split points between ITugay and AvonWyss

Please leave any comments here within the next seven days.

PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!

Thanks,

geobul
EE Cleanup Volunteer
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

A lot of questions regard threads in Delphi.   One of the more specific questions is how to show progress of the thread.   Updating a progressbar from inside a thread is a mistake. A solution to this would be to send a synchronized message to the…
Creating an auto free TStringList The TStringList is a basic and frequently used object in Delphi. On many occasions, you may want to create a temporary list, process some items in the list and be done with the list. In such cases, you have to…
This Micro Tutorial will teach you how to censor certain areas of your screen. The example in this video will show a little boy's face being blurred. This will be demonstrated using Adobe Premiere Pro CS6.
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…

920 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

15 Experts available now in Live!

Get 1:1 Help Now