Board index » cppbuilder » Various sorting of TRichEdit->Lines - Is there any **faster** solution as mine...?

2005-08-29 09:49:20 PM
cppbuilder5
dear builders,
i've got a filter programm that really need to handle files
(database-textfiles) with a
size-average of: 1,5 - 2 MByte each...
with the below functions i need 5-6 min (and more..) on a P4 with 2,0 GH'z
and 512 MByte Ram (!!!)
i believe the slow time-duration doesn't have to do something with my
current hardware-configuration,
because i've tested the programm on several machines with diffrent
hardware-configuration, i get ~ nearly
the same time duration for the results...
is there something that i can optimize....?
- does the VCL controll itself ( TRichEdit )caising the slow processing of
the sorting...?
- will the STL help me in this case...? or do the both use the same
algorythm (QuickSort) to sort...?
- can i add the strings into something else as VCL's StringList, for example
a vector...?
or woulndn't that make sense.....?
---->sList->AddStrings(rePreview->Lines); // i guess this is also causing
the slow processing...right ?
Oren
PS: i use BCB 3, thats why CustomSort(..) is declared here...
/*************************************************************************/
// the algorythm...
typedef int __fastcall (*TStringListSortCompare) (TStringList *List, int
Index1, int Index2);
void __fastcall StringListQuickSort(TStringList *List, int L, int R,
TStringListSortCompare SCompare)
{
int I, J, P;
do
{
I = L; J = R; P = ((L + R)>>1);
do
{
while(SCompare(List, I, P) < 0) ++I;
while(SCompare(List, J, P)>0) --J;
if(I <= J)
{
List->Exchange(I, J);
if(P == I) P = J; else if(P == J) P = I; ++I; --J;
}
}
while(I <= J);
if(L < J) StringListQuickSort(List, L, J, SCompare); L = I;
}
while(I < R);
}
void __fastcall CustomSort(TStringList *List, TStringListSortCompare
SCompare)
{
StringListQuickSort(List, 0, List->Count-1, SCompare);
}
/********************* Callbacks...
*****************************************/
int __fastcall AlphaCallback(TStringList *List, int Index1, int Index2)
{
AnsiString Line1 = List->Strings[Index1], Line2 = List->Strings[Index2];
int multiplier;
if(frmMainUnit->cmdSortUp->Down) multiplier = 1;
else multiplier = -1;
return (AnsiCompareStr(Line1, Line2) * multiplier);
}
int __fastcall LengthCallback(TStringList *List, int Index1, int Index2)
{
AnsiString Line1 = List->Strings[Index1], Line2 = List->Strings[Index2];
int multiplier;
if(frmMainUnit->cmdSortUp->Down) multiplier = 1;
else multiplier = -1;
return ((Line1.Length() - Line2.Length()) * multiplier);
}
//...
//....MANY OTHERS........
//...
void __fastcall TfrmMainUnit::WhichSort(SortType whichType)
{
static TStringListSortCompare Callbacks[] = { NULL, AlphaCallback,
LengthCallback };
TStringList *sList = new TStringList;
try
{
Screen->Cursor = crHourGlass;
try
{
sList->Duplicates = dupAccept;
sList->AddStrings(rePreview->Lines);
if(whichType != sort_None) CustomSort(sList, Callbacks[whichType]);
rePreview->Lines->Assign(sList);
}
__finally
{
Screen->Cursor = crDefault;
}
}
__finally
{
delete sList;
}
}
void __fastcall TfrmMainUnit::cmdSort_AlphaClick(TObject *Sender)
{
WhichSort(sort_Alpha);
rePreview->SelStart = 0;
rePreview->SetFocus();
}
void __fastcall TfrmMainUnit::cmdSort_LineLenClick(TObject *Sender)
{
WhichSort(sort_Lines);
rePreview->SelStart = 0;
rePreview->SetFocus();
}
//...
//....MANY OTHERS........
 

Oren Halvani wrote:
might be a little bit more efficient then yours but I wouldn't expect
miracles.
vector might become slow if they are small this is not a problem.
Remember you do a lot of swapping in quicksort.
A vector os AnsiStrings is more efficient memory wise.
the issue but allocating thousands of memory blocks is.
quicksort because it is the operation which is performed most often.
Because of this I have two tips. First remove the local copies of the
strings and use directly the strings in the list. Second remove the if
statements instead calculate the multiplier once outside the function
and use the value inside the compare functions.
Eelke
 

"Eelke" < XXXX@XXXXX.COM >wrote in message news:431459ee$ XXXX@XXXXX.COM ...
i'll see if these hints taking effect on the speed...
Oren
 

{smallsort}