Re: [Q] To initialise or not.

[mjp@itd.dsto.gov.au]

"Thorsten Behrens" <thorsten.behrens@dorunth.hb.north.de> writes:

>I tend to give all my declarations some initial value (if possible) _and_
>an initial comment (giving a shorter or longer text about its usage and
>the background of this variable). In my eyes this saves me from having
>non-initialized variables (causing errors which are sometimes nasty to
>find) and it saves people reviewing my sources from wasting too much time
>to guess what I was thinking when "inventing" a variable (normally, I would
>not use a variable called 'X', but instead would have called it
>'Some_Meaningful_Name').

I think what to do depends on the strenght of your compiler.

Ideally, the hardware would have store both a value, and a
bit indicating whether the value was valid (initialised) or
not. If this hardware support is not provided, hopefully,
your compiler will do a dataflow analysis and flag "used but
not set" variables, even this can fail in things like loops or
assignments in conditionals.

I always prefer to force a detectable error so for instance I
would tend to initialise to an absurd value. E.g. for a
divisor variable, I would initialise to 0 in the declarations,
that way if it is used before set it will cause a divide by
zero exception. Of course not all operations will cause such
obvious errors and in other cases I would tend to use such an
out of bounds value that you would at least see the error in
the output and go looking for it.

The really insidious errors are the ones that don't look like
a problem, i.e. appear plausable.

Michael

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