Solved

Reading strings

Posted on 2004-05-02
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Last Modified: 2010-04-05
I have this code that opens a text file and reads every line and looks for $ symbol
then it reads bacwards until it finds a space and foreward the same way, and copys the string in between the spaces  how can i change it to read backwards until it finds @ and foreward until it finds a @  symbol?

is this the right way, or do i need to use blockread ?

var
  r : TextFile;
  F : TextFile;
  S : STRING;
  i : integer;
begin

    AssignFile(F,File1);
  Reset(F);
   REPEAT
  // REPEAT
   Readln(F,S);
 I := Pos('$',S);
 if I > 0 then begin
   while (I > 0) and (S[I] <> '@ ') do Dec(I);
   S := Copy(S,I + 1,Length(S) - I);
   I := Pos('@ ',S + '@ ');
   A := Copy(S,1,I - 1);
    // S := Copy(S,I,Length(S) - I + 1);
 end;
   Writeln(r,a);
 // showmessage(a);
 //UNTIL (i)=0;
 UNTIL Eof(F);
 CloseFile(F);
 end;
0
Comment
Question by:herd_bone
  • 3
  • 2
5 Comments
 
LVL 12

Expert Comment

by:esoftbg
ID: 10974933
procedure TForm1.SpeedButton1Click(Sender: TObject);
var
  r : TextFile;
  f : TextFile;
  A : STRING;
  S : STRING;
  I : integer;
  J : integer;
  K : integer;
begin
  J := 0;
  AssignFile(r, 'Q_20975533_r.txt');
  Rewrite(r);
  AssignFile(F, 'Q_20975533.txt');
  Reset(f);
  repeat
    Readln(f, S);
    I := Pos('$', S);
    if I > 0 then
    begin
      J := I;
      while (J > 0) and (S[J] <> '@') do
        Dec(J);
      K := I;
      while (K < Length(S)) and (S[K] <> '@') do
        Inc(K);
      if (J>0) then
      begin
        A := Copy(S, J+1 , K-J-1);
        S := Copy(S, K, Length(S) - K + 1);
      end;
    end;
    if (J>0) then
      Writeln(r, A);
  until Eof(f);
  CloseFile(r);
  CloseFile(f);
end;
0
 

Author Comment

by:herd_bone
ID: 10975221
It works good, one question though, why does it put too many of the same strings in the list
if i read a file that has alot of lines, it puts duplicate strings into my result..
0
 
LVL 12

Expert Comment

by:esoftbg
ID: 10975321
I did try a simple text file wich contains 3 rows and only the 3-d contains '@ and foreward $ until it finds a @':

I have this code that opens a text file and reads every line and looks for $ symbol
then it reads bacwards until it finds a space and foreward the same way, and copys the string in between the spaces  
how can i change it to read backwards until it finds @ and foreward $ until it finds a @  symbol?

I guess my code is not perfect. I need to try with more complex text file.
emil
0
 
LVL 12

Accepted Solution

by:
esoftbg earned 110 total points
ID: 10975395
try this, I tested with more complex text file:

procedure TForm1.SpeedButton1Click(Sender: TObject);
var
  r : TextFile;
  f : TextFile;
  A : string;
  S : string;
  I : integer;
  J : integer;
  K : integer;
begin
  AssignFile(r, 'Q_20975533_r.txt');
  Rewrite(r);
  AssignFile(F, 'Q_20975533.txt');
  Reset(f);
  repeat
    Readln(f, S);
    I := Pos('$', S);
    while (I > 0) do
    begin
      J := I;
      while (J > 0) and (S[J] <> '@') do
        Dec(J);
      K := I;
      while (K < Length(S)) and (S[K] <> '@') do
        Inc(K);
      if (J>0) then
      begin
        A := Copy(S, J+1 , K-J-1);
        Writeln(r, A);
      end;
      S := Copy(S, K+1, Length(S) - K + 1);
      I := Pos('$', S);
    end;
  until EOF(f);
  CloseFile(r);
  CloseFile(f);
end;
0
 

Author Comment

by:herd_bone
ID: 10980942
Thanks esoftbg.
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