sudhakar_koundinya
asked on
How to clear the memory out side the dll.
Hi,
I am using the heap memory in dll and after usage of that i want to clear that memory. But when i try to use freemem or dispose procedures in the apllication, it is raising the errors. Please comment on this where i made mistake.
And this is sample code
procedure parseMethod(aInputStream:P Char; aFormattedTextSize:longint ; var aParsedText:PChar; var aErrorNumber:Integer);stdc all;extern al 'MyParse.Dll' ;
//external application sample code
procedure TForm1.btnSaveClick(Sender : TObject);
begin
parseMethod(tempBfr, intsize, aOutPutStr, aOutPutError);
ShowMessage( aOutPutStr);
FreeMem(aOutPutStr,strLen( aOutputStr ));
end;
//dll code
procedure parseMethod( inBuffer:PChar; strLength:LongInt; var outBuffer:PChar; var enoint:Integer);cdecl;
var
objParser:TParsePDF;
begin
try
objParser:=TParser.Create (inBuffer,strLength); //initialise the parser
begin
objParser.Parse (outBuffer,enoint); //parse the data
// *********** here outBuffer Memory will be allocated in Parse Procedure ******** //
enoint:=0;
end
except
On error: exception do
begin
if strlen(outBuffer)> 0 then
begin
enoint:=0;
end
else
begin
strcopy(outBuffer,''); //false document
enoint:=-1; // set error flag
end;
end;
end;
end;
Thanks
Koundinya
I am using the heap memory in dll and after usage of that i want to clear that memory. But when i try to use freemem or dispose procedures in the apllication, it is raising the errors. Please comment on this where i made mistake.
And this is sample code
procedure parseMethod(aInputStream:P
//external application sample code
procedure TForm1.btnSaveClick(Sender
begin
parseMethod(tempBfr, intsize, aOutPutStr, aOutPutError);
ShowMessage( aOutPutStr);
FreeMem(aOutPutStr,strLen(
end;
//dll code
procedure parseMethod( inBuffer:PChar; strLength:LongInt; var outBuffer:PChar; var enoint:Integer);cdecl;
var
objParser:TParsePDF;
begin
try
objParser:=TParser.Create (inBuffer,strLength); //initialise the parser
begin
objParser.Parse (outBuffer,enoint); //parse the data
// *********** here outBuffer Memory will be allocated in Parse Procedure ******** //
enoint:=0;
end
except
On error: exception do
begin
if strlen(outBuffer)> 0 then
begin
enoint:=0;
end
else
begin
strcopy(outBuffer,''); //false document
enoint:=-1; // set error flag
end;
end;
end;
end;
Thanks
Koundinya
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oops,
robert was a bit faster... :)
robert was a bit faster... :)
ASKER
Yes Robert and Cynna,
I did the same. But you are saying that ShareMem should be first unit to be included .If this is the mistake i made, I will check that.
But I have one doubt, why it should be the first unit to be included in both applications?
Thanks
Koundinya
I did the same. But you are saying that ShareMem should be first unit to be included .If this is the mistake i made, I will check that.
But I have one doubt, why it should be the first unit to be included in both applications?
Thanks
Koundinya
sudhakar_koundinya,
> But I have one doubt, why it should be the first unit to be included in both applications?
ShareMem contains an initialization section that installs the memory manager, and we want that to occur before any memory is allocated from any other unit, right?
Also, use it as a first unit in your APP, that is, change your .dpr file like this:
program Project1;
uses
ShareMem, // <---- !!! (only here, not in Unit1, Unit2, ...)
Forms,
Unit1 in 'Unit1.pas' {Form1};
(.. etc ..)
> But I have one doubt, why it should be the first unit to be included in both applications?
ShareMem contains an initialization section that installs the memory manager, and we want that to occur before any memory is allocated from any other unit, right?
Also, use it as a first unit in your APP, that is, change your .dpr file like this:
program Project1;
uses
ShareMem, // <---- !!! (only here, not in Unit1, Unit2, ...)
Forms,
Unit1 in 'Unit1.pas' {Form1};
(.. etc ..)
ASKER
Thanks robert :)
SIMPLE:
--------------
Type (in DLL and App):
uses ShareMem, .... in your uses clause before anything else.
DETAILED:
---------------
If you do not use ShareMem or build all modules with run-time packages each module will have its own instance of the RTL memory manager. Therefore, DLL and your app have separate MMs, and each one is operating on different memory pool. Consequently, allocating mem in DLL and freeing it in App produces error.
So, you should use ShareMem as a first unit in DLL and App.
Go to Delphi help index and type 'ShareMem', for further info.