Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!sharkey!atanasoff!hascall
From: hascall@atanasoff.cs.iastate.edu (John Hascall)
Newsgroups: comp.arch
Subject: Re: String lengths
Message-ID: <762@atanasoff.cs.iastate.edu>
Date: 5 Feb 89 17:47:17 GMT
References: <6133@columbia.edu> <5124@aldebaran.UUCP> <7@microsoft.UUCP> <213@nbires.nbi.com> <38@microsoft.UUCP> <219@nbires.nbi.com> <14331@cup.portal.com>
Reply-To: hascall@atanasoff.cs.iastate.edu (John Hascall)
Organization: Iowa State U. Computer Science Department, Ames, IA
Lines: 31

In article <14331@cup.portal.com> PLS@cup.portal.com (Paul L Schauble) writes:

>Since it was mentioned in the Endian Wars, does anyone know why C uses the
>null terminated string rather than an explicit length? It seems like such
>an odd choice considering that

>  - It removes a character from the character set, a source of many C
>    bugs, and

   Agreed.

>  - All machines I know of that have character string instructions want
>    the length of the string. This forces the string primitives to first
>    scan for null, a time wasting operation.

   I assume you mean something like:

      +------+---+---+---+---+---+---+---+---+---+---+---+---+---+
      |length| H | E | L | L | O | , |   | W | O | R | L | D | \n|
      +------+---+---+---+---+---+---+---+---+---+---+---+---+---+

  but, what size would you use for "length", a byte? a word? a longword?

  I suspect that some of these machines' instructions expect different
  sized operands for the length.

  Also, to quote K&R: "C was originally designed ... on the DEC PDP-11",
  a machine with no string instructions.

  John Hascall
  ISU Comp Center