Re: "Subtract C, add Ada"

[dobrien@seas.gwu.edu (David O'Brien)]

Samuel Mize (smize@Starbase.NeoSoft.COM) wrote:
: In article <1995Jan23.154631.6702@sei.cmu.edu>,
: Robert Firth <firth@sei.cmu.edu> wrote:
: >In article <3fo2ot$su2@miranda.gmrc.gecm.com> bill@valiant (R.A.L Williams) writes:
: >
: ...
: >> 1. It allows your code to be more compact.
: >
: >>    NB DONT confuse compactness with poor layout! I find that, for example:
: >>
: >>       while ((c = getchar()) == ' ')
: >>       {
: >>          /* count spaces */
: >>       }
: >>

: This bit of code is based on the assumption that there is a null at
: the end of your string -- oh, but this is a file read.  C guys:
: does C return a null if you getchar at EOF?  Or is this a misplaced
: array idiom?

This code is *not* based on the assumption that there is a ASCII NUL at the
end of the string.  There is nothing here that implies a string.  A
string being a series of characters terminated by an ASCII NUL
character.  Nor is this a file read.  getchar reads from the standard
input.  This would be interactive input unless the input has been
redirected to a file.

C (what I believe you are actually asking is does getchar return a NUL
at EOF), returns the EOF "character" at EOF.  If the above code was
reading from a file, the loop would terminate at EOF since EOF is not
the same value as a space character.  So the code fragment is still ok
with redirected input.

-- David O'Brien	(dobrien@seas.gwu.edu)