>Andy, I never heard of any part of the C spec that guarantees zeroed
>variables at startup! I have used Borland Turbo C++ for several years for
>programming PCs and I never remember any such guarantee. IN fact, I seem to
>remember just the opposite being said (i.e.,you must initialize the vars
>yourself,as opposed to other higher-level languages such as BASIC).

For automatic variables, no, but static duration variables, yes.

ANS X3.159-1989 3.5.7 Initialization
        "If an object that has automatic storage duration is not initialized
explicitly, its value is indeterminate. If an object that has static
storage duration is not initialized explicitly, it is initialized
implicitly as if every member that has arithmetic type were assigned 0 and
every member that has pointer type were assigned a null pointer constant."

It is not unreasonable, IMO, for compilers for small processors to, at
least optionally, waive the implicit initialization of static duration
objects, as it's good style to explicitly initialize any variable upon
whose startup-value the program will depend and initializing a bunch of
locations to zero when it's not necessary can chew up a lot of cycles at
startup that could be put to better use.

        Jim

James Grosbach
Development Systems
Microchip Technology
james.grosbach@microchip.com