How to save only a particular item in the tstringlist to a file

Question

Here is my code.

var
  filehan : Textfile;
  i : Integer;
  LineOfText   : String;
  tsl : TStringList;
  Name, Emp_id : string;
begin
  stf := TStringList.c         


        

Answer 1

I know there are more elegant variations but these should be simple and understandable.

try your variables is not not to be confused

  Assignfile ( filehan, 'EMP.txt');
  Reset ( filehand );
  CloseFile (FFile);

One filehan and the other filehand and FFile

The particular characteristics of a TStringList, your SubStrings function needs only one line of code.

sList.text:=StringReplace(AString,ADelimiter,#13#10,[rfReplaceAll]);

• only 4 variables.
• only 1 TStringList .

Tested with Delphi 5

var
  LineOfText   : String;
  sList : TStringList;
  filehand,Outfilehand: text;

function SubStrings(AString: String; ADelimiter: Char; var sList: TStringList):Boolean;
begin
  sList.text:=StringReplace(AString,ADelimiter,#13#10,[rfReplaceAll]);
end;

begin
  sList := TStringList.Create;
  Assignfile ( filehand, 'EMP.txt');
  Assignfile ( Outfilehand, 'FSTRING.txt');
  Reset ( filehand );
  Rewrite(Outfilehand);
  try
  While not EOF(filehand) do
  begin
    ReadLn  ( filehand, LineOfText );
    LineOfText:=StringReplace(LineOfText,': ',':',[rfReplaceAll]);
    LineOfText:=StringReplace(LineOfText,' :',':',[rfReplaceAll]);
    if pos(':210:',LineOfText)>0 then begin
       substrings(LineOfText, ':' ,sList);
        if (sList.Count=6) then
           if (sList[3]='210') then writeln(Outfilehand,sList[0]+';'+sList[1]);
    end;
  end;
  finally
  sList.Free;
  CloseFile (filehand);
  CloseFile (Outfilehand);
  end;

UPDATE:

I understood the question so that you are only in the row with 210 field value are interested. If you want all the lines in the new file, replace .

if pos(':210:',LineOfText)>0 then begin
        substrings(LineOfText, ':' ,sList);
            if (sList.Count=6) then
               if (sList[3]='210') then writeln(Outfilehand,sList[0]+';'+sList[1]);
end;

with

substrings(LineOfText, ':' ,sList);
   if (sList.Count=6) then
         if (sList[3]='210') then 
         writeln(Outfilehand,sList[0]+';'+sList[1]+';'+sList[4]+';'+sList[5]);
   if (sList.Count=3) then
         writeln(Outfilehand,sList[0]+';'+sList[1]);

Based on the size or value of sList[3] :

• You can self define which fields are written to FSTRING.txt.

UPDATE2:

How I would do it.

var
  ParsedText   : String;
  inList,outList,sList : TStringList;
  i:integer;

function SubStrings(lineText: String; var sList: TStringList):String;
begin
  result:='ERROR';
  lineText:=StringReplace(lineText,': ',':',[rfReplaceAll]);
  lineText:=StringReplace(lineText,' :',':',[rfReplaceAll]);
  sList.text:=StringReplace(lineText,':',#13#10,[rfReplaceAll]);
    if (sList.Count=6)    then
      if (sList[3]='210') then result:=sList[0]+';'+sList[1]+';'+sList[4]+';'+sList[5] else
                               result:=sList[0]+';'+sList[1];
    if (sList.Count=3)    then result:=sList[0]+';'+sList[1];
end;

begin
  inList  := TStringList.Create;
  outList := TStringList.Create;
  sList   := TStringList.Create;
  try
  inList.LoadFromFile('EMP.txt');
    for i:= 0 to inList.Count-1 do begin
     ParsedText := SubStrings(inList[i],sList);
     if ParsedText <> 'ERROR' then outList.Add(ParsedText);
    end;
  outList.SaveToFile('FSTRING.txt');
  finally
  inList.Free;
  outList.Free;
  sList.Free;
  end;
end;