TextFile ReWrite error in Lazarus - lazarus

Question

I have two files - one contains a number of short strings (that I call Items) and the other contains the IDs for these short strings. I also have a number of other files, each of which contains a very long string that is broken up into thousands of smaller strings by means of line breaks. I need to find the number of times each short string ("Item") occurs in each of the large string files, as well as the starting and ending position for each hit.
My first task is to remove the line breaks in the large files so that the hits do not straddle across two or more smaller strings, and then find the number of occurrences and start and end positions of each short string in the large strings, and report these results using the ID numbers for each short string.
I am getting a EInOutError (Access Denied) error apparently at the ReWrite(ResultFile) line (in the bottom half of the second procedure in the code below). Not sure why. I can see the file created for the results of the first long string, but it is blank. Here is the code; pretty simple and straightforward, actually. Thanks.
procedure TForm1.OpenStrCmdBtnClick(Sender: TObject);
begin
if OpenDialog1.execute then OpenStrEditBx.Text := OpenDialog1.FileName
else ShowMessage('Cannot open file!');
end;
procedure TForm1.FindItemfCmdBtnClick(Sender: TObject);
var
I, LenItem, NumTimes, offset: integer;
Extension, FileName, Dir, Str, Item, ID: string;
TempList, IDList, ItemList: TStringList;
searchResult: TSearchRec;
ResultFile: TextFile;
begin
IDList := TStringList.Create;
ItemList := TStringList.Create;
IDList.LoadFromFile('D:\...\IDs.txt');
ItemList.LoadFromFile('D:\...\Items.txt');
try
Dir := ExtractFilePath(OpenStrEditBx.Text);
//concatenate each line in each str sequence to get full string
if FindFirst(Dir + '*.txt', faAnyFile, searchResult) = 0 then
repeat
Extension := ExtractFileExt(OpenStrEditBx.Text);
FileName := StringReplace(searchResult.Name, Extension, '', [rFReplaceAll, rFIgnoreCase]);//remove file extension to get only file name
TempList := TStringList.Create;
TempList.LoadFromFile(Dir + searchResult.Name);
Str := '';
for I := 1 to TempList.Count-1 do // I <> 0 to ignore ID in first line
begin
Str := Str + TempList[I];
ProgressBar1.Position := (ProgressBar1.Position + 10) mod ProgressBar1.Max;
end;
TempList.Free;
//Find number and location of occurrences of each Item
for I := 0 to ItemList.Count-1 do
begin
Item := ItemList[I];
LenItem := Length(Item);
ID := IDList[I];
NumTimes := 0;
Offset := PosEx(Item, Str, 1);
AssignFile(ResultFile, 'D:\...\' + FileName + '.txt');
ReWrite(ResultFile);
while Offset <> 0 do
begin
inc(NumTimes);
if NumTimes > 0 then
WriteLn(ResultFile, 'The ' + IntToStr(NumTimes) + 'th occurrence of ' + 'ID# ' + ID + ' is from Position# ' + IntToStr(Offset) + ' to Position# ' + IntToStr(Offset + LenItem- 1) + ' in ' + FileName);
Offset := PosEx(Item, Str, Offset + LenItem);
end;
WriteLn(ResultFile, 'ID# ' + ID + ' occurs ' + IntToStr(NumTimes) + ' number of times in ' + FileName);
end;
CloseFile(ResultFile);
ShowMessage(FileName + ' done!');
until FindNext(searchResult) <> 0;
FindClose(searchResult);
finally
IDList.Free;
ItemList.Free;
end;
end;