I can't get my function to work:

Function FetchLine(var CFile:file):Boolean;
 var
   TmpChar:Array[1..2] of Char;
   EndRead:Boolean;
 begin
   FLength:=0;
   EndRead:=False;
   FetchLine:=False;
   repeat
    BlockRead(CFile,TmpChar,1,NumRead);
    Writeln(TmpChar[1]); {here for debugging}
    If (TmpChar[1]<>#13) and (TmpChar[1]<>#10) and (NumRead>0) then
                  begin
                    Inc(FLength);
                    FBuff[FLength]:=TmpChar[1];
                    Writeln('Length=',FLength);  {here for debugging}
                  end;
    If (TmpChar[1]=#13) or (TmpChar[1]=#10) then
          begin
           EndRead:=True;
           FetchLine:=True;
          end;
    If (NumRead=0) or (FLength>=SizeOf(FBuff)) then EndRead:=True;
   until EndRead;
 end;

It is begin called with:
     Assign(DescFile,D+'DESCRIPT.ION');
     Reset(DescFile);
      TmpStr:='';
      While FetchLine(DescFile) and (UCASEStr(TmpStr)<>DirInfo.Name) do
        begin
          If FLength>100 then
              A:=CA2Str(1,100)
             else
              A:=CA2Str(1,FLength);
          TmpStr:=Copy(A,1,Pos(' ',A)-1);
        end;
     Close(DescFile);

The problem is that the FetchLine function locks up after nearly
finishing adding the first character from the file.  Why I don't know.

HELP?

AA>I can't get my function to work:

AA>Function FetchLine(var CFile:file):Boolean;
AA> var
AA>   TmpChar:Array[1..2] of Char;
AA>   EndRead:Boolean;
AA> begin
AA>   FLength:=0;
AA>   EndRead:=False;
AA>   FetchLine:=False;
AA>   repeat

      <code snipped>

AA>   until EndRead;
AA> end;

I didn't look at your complete code, but a suggestion for avoiding
problems when reading a file within a loop is to use a WHILE/DO loop
rather than a REPEAT/UNTIL. The reason is that the latter will always
execute at least once, and so if the file is empty it will read past the
end of the file, causing problems.

        -- Kim Forwood --

In article <Pine.SOL.3.91.960403201205.29198B-100...@fan1.fan.nb.ca>

The first thing that caught my eye is entering into a file read with a
repeat loop.  Wouldn't be too bad, except the test foe an eof condition
is made at he end of the loop.  There is a lot of code that is being
executed even if you read nothing!

I almost {*word*88}d when I saw that you were reading an untyped file one
character at a time.  This really isn't an error and I try not to
critize the base design but this one took my breath away.  If you're
trying to create a sloooow program, you are on the right track. :)

If you want to read one character at a time without the work of
buffering the input, I suggest that you use a text file.  At least by  
default it buffers 128 characters.

You need to re-think what you are doing.  A repeat loop executes once,
so if the file is empty, you're cooked!  That's why you see most code
using a while loop for reading files.

                      ...red

The fact that untyped file has an undefined record size must be added
to manuals in BIG AND FAT letters, as well as to all the FAQ's on
Turbo Pascal and derivatives.

--
Zhenya Sorokin

On 3 Apr 1996, Kim Forwood wrote:

Problem solved.   Thanks for the advice to all that replied.

AA>On Thu, 4 Apr 1996, R. E. Donais wrote:

AA>> we can only guess what it is all about.  For example, Reset(DescFile)
AA>> implies that it is a Text file, but is passed as an untyped file.  The
AA>> program appears to use a lot of global variables, not of which you
AA>> supplied, etc.

AA>I didn't bother including them no, because i can't see how they would
AA>cause the computer to lock up.   All files have been defined as "file",
AA>untyped.

For proper analysis of a problem, it's important to include *all*
information pertaining to the given problem, in order to properly
determine that it isn't part of the problem.

AA>> The first thing that caught my eye is entering into a file read with a
AA>> repeat loop.  Wouldn't be too bad, except the test foe an eof condition
AA>> is made at he end of the loop.  There is a lot of code that is being
AA>> executed even if you read nothing!

AA>Took out EOF() checks because they were locking up the computer before it
AA>even got to the loop.

A very bad reason. I would imagine that your use (or mis-use) of EOF was
at least part of the problem to begin with.

AA>> I almost {*word*88}d when I saw that you were reading an untyped file one
AA>> character at a time.  This really isn't an error and I try not to
AA>> critize the base design but this one took my breath away.  If you're
AA>> trying to create a sloooow program, you are on the right track. :)

AA>Only way I can figure out how to read a text file since no one in this
AA>newsgroup helped me with such after posting twice.  I'll try to read it in
AA>with larger blocks when/if I ever figure out how, but as far as I can tell
AA>that will take about 1000 lines of code because I guess I would need to
AA>including Seeking over and over, and have to keep track more of where I
AA>am in the file.

Have patience. Not everyone that is capable or willing to take the time
to help can respond immediately. It also helps to present the problem
clearly, showing that you've put some thought into it already (not
saying that you didn't). Have a look at BlockRead/BlockWrite if you
haven't yet.

AA>> You need to re-think what you are doing.  A repeat loop executes once,
AA>> so if the file is empty, you're cooked!  That's why you see most code
AA>> using a while loop for reading files.

AA>Perhaps if it wouldn't lock up.

If it's locking up then there is something wrong with your code. It's
guaranteed that a REPEAT/UNTIL loop will eventually cause problems down
the road.

        -- Kim Forwood --

On 4 Apr 1996, Kim Forwood wrote:

    First off, it appears you want to scan the file character by character.
Thus use a blocksize of 1 or else Borland Pascal will default to 128
char blocks during blockread/write:

   { example code }
   var
       DescFile : File;
   ...

   Assign(DescFile,D+'DESCRIPT.ION');
   Reset(DescFile,1);   { use blocksize 1 for untyped files }

   ...

   { end example code }

    I believe the blockread of length 1 in your code was destroying the
stack and who knows what else by reading 128 chars into TmpChar which
only has a size of 2 bytes. Good luck.

Ray

In article <Pine.SOL.3.91.960403201205.29198B-100...@fan1.fan.nb.ca>,

Heres a stratigy I use on reading straight text with CR/LF (#13#10) line
delimiters.

{ Return a text string to caller }
Fucntion ReadFLN(Var F:File) :String;
Var
  I
  BtsRead : Integer;
  StrRead : String;                 { Var so read/buffer string to                                 }
  FPOs    : Longint;                { Current file Position Var                                    }
Begin
  S := '';
  If Not(EOF(F)) Then               { Just a little caution here }
  Begin
    FPos := FilePos(F);             { Set Up for "Quiet" read                                      }
    Blockread(F,S[1],255,BtsRead);  { 3 things here 1.) No Big error if less than 255 bytes read   }
                                    {               2.) read MAX a String will hold.               }
                                    {               3.) Read DIRECTLY into our variable            }
    S[0] := Char(BtsRead);          { Set inital string length to number of bytes read             }
    I := POS(#13,S);                { Use Pos to search for #13 (CR) first delim.                  }
    If I > 0 Then
      S[0] := Char(I-1);            { Set string length to search results                          }
    { Heres the "Quiet" part }
    Seek(F,FPos);                   { Reset Filepointer to inital/entry position                   }
  End;
  ReadFLn := S;                     { Return results                                               }
End;

There a MUCH better ways of doing this job, but this one should give you a starting place.  
This Routine will be much faster, on average, than reading one chatacter at a time.  
A footnote her would have to be with tracking the File Cursor/pointer.  To read the next string,
Adjust the next seek loaction to the length of the returned string.  I think this will do in a
pinch.