[fpc-pascal]Strange Segfault...

Alan Mead cubrewer at yahoo.com
Mon Jul 14 15:48:06 CEST 2003

I'm running into this string problem as well.  I'd like to use
strings longer than 255 but I get strange errors like:

[amead at alan seq-bayes]$ fpc mcmc3pl.pas
Free Pascal Compiler version 1.0.6 [2002/05/23] for i386
Copyright (c) 1993-2002 by Florian Klaempfl
Target OS: Linux for i386
Compiling mcmc3pl.pas
Assembling mcmc3pl
Linking mcmc3pl
mcmc3pl.o(.text+0x147): undefined reference to
mcmc3pl.o(.text+0x17c): undefined reference to `FPC_VAL_SINT_LONGSTR'
mcmc3pl.o(.text+0x243): undefined reference to
mcmc3pl.o(.text+0x278): undefined reference to `FPC_VAL_SINT_LONGSTR'
mcmc3pl.pas(215) Error: Error while linking
Closing script ppas.sh

[amead at alan seq-bayes]$ fpc test_string500
Free Pascal Compiler version 1.0.6 [2002/05/23] for i386
Copyright (c) 1993-2002 by Florian Klaempfl
Target OS: Linux for i386
Compiling test_string500.pas
test_string500.pas(15,13) Fatal: Internal error 8888

These errors disappear when I edit the string definitions back to
length 255 or less. Should I just avoid using longer strings or is
there a compiler switch I have to include?  Or is there a tutorial on
FPC strings (I never used Delphi much)?  Or is this behavior fixed in


--- Matt Emson <memsom at interalpha.co.uk> wrote:
> > Yes and no. Why is it so bad to write a function in that way ? It
> could
> > of course be written two different ways, but I'd rather this way
> where I
> > modify the string passed to the function.
> >
> > Explain it to me :) (I'm the only one that works on this project
> of
> > ~30,000 LOC, so I don't see any problem)
> Turbo Pascal and Delphi 1 had a type called 'String'. This was
> limited to
> 255 chars, size of 256 chars, and position 0 holds the strings
> length.
> Delphi 2+ has a type called shortstring that behaves in exactly the
> same way
> as the old style string.
> Delphi 2+ altered the string type to be a pointer to a chunk of
> memory, and
> added a whole load of compiler magic to make strings automatically
> grow and
> shrink, added reference counting and 'copy of change' functionality
> (the
> last two to aid in not having to copy a string until someone alters
> it.)
> This is where your problem lies.
> Because FPC mimics Delphi string functionality, basically you'll
> end up with
> similar results.
> You'd be much better off Returning a value, and thereby avoiding
> the
> potential for big allocation/deallocations. That or use
> shortstrings.
> Matt
> _______________________________________________
> fpc-pascal maillist  -  fpc-pascal at lists.freepascal.org
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