Hallo Martin, Du schriebst am Fri, 13 Apr 2012 08:10:15 +0200:
> > That's nonsense. Implemented correctly, _any_ index base gives identical > > speed - you _don't_ implement it using offset calculation from the first ... > You probably should have a look into the disassembler listings of your > programs and the FPC RTL. That was not a description of the actual implementation by FPC, but one giving the "state of the art" (a very old art, indeed, as it was common knowledge half a century ago - not longer though, it seems?). > Why do you think Pascal string index is one based in the first place? > Because it is a zero based index to the old shortstring data where > <shortstring>[0] denotes the length byte, do you remember? I _know_ this, as I used this over and over for getting and setting the length of strings in Tubo Pascal, until around version 6 it was "deprecated" (as it's called today) and replaced by "SetLength" for setting - getting was always possible by the "Length" function. But the original justification for the indexing scheme was said to be that the actually used character data should be counted "naturally", starting at 1, and the "0th" element was simply used because then it could be implemented as a simple array. With the "shortstring" type, accessing the count by index thus always required/s a type conversion between byte and char (functions "ord" and "chr"). > <shortstring>[0] denotes the length byte, do you remember? An AnsiString Anistrings were presented as "opake" types, where it was _not_ meant to be possible to access the fields directly, specifically not the length value. The _order_ and arrangement of the fields was not even officially specified in the beginning. > How many lines of string manipulating code did you write? I wrote Don't know. > countless. And often I switch to the C-notation (pchar(pointer > (<thepascalstring>)) [index]) because of performance and convenience > reasons. Yes, that's exactly the opposite of my style. I prefer the "Pascal" way, as introduced by UCSD Pascal and generalized and made public by former Borland. I prefer _safe_ string handling, and it's been fast enough for my purposes everytime in the past. I also prefer _static_ strings (and other data types), because most of my programming pertains to small systems with limited resources, which often cannot handle the large overhead dynamic memory incurs. (In addition, at least the "Pascal" string handling is inherently safe in contrast to the C-style way. This means that programs using it are _not_ prone to buffer overflows or out-of-bounds accesses which are so well regarded among the writers of malware programs. Similar safeguards have only recently been added to newer C versions and variants, such as C#.) -- (Weitergabe von Adressdaten, Telefonnummern u.ä. ohne Zustimmung nicht gestattet, ebenso Zusendung von Werbung oder ähnlichem) ----------------------------------------------------------- Mit freundlichen Grüßen, S. Schicktanz ----------------------------------------------------------- ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ mseide-msegui-talk mailing list mseide-msegui-talk@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mseide-msegui-talk
