Re: Software Vendors

I "made sure" my program was bug free by analyzing the possible
input that it could receive, checking the logic for all, and testing.
You also need to understand that for any input you basically need
to test for seven possible cases.  *hival, *loval, some middle value,
> *hival, < *loval, invalid data type, empty.

If you have all those covered on your input, your input can not
mess you up.

Then you look at your calculations, do you handle all cases of
data?  *hival times *hival, *hival times *loval, *loval times *loval,
and if you allow empty you need to special case it in your code.

Then you check your output, and does it accept all possible values.

That is for user input, calculation, and output.  Then there are things you
check for files, does file exist, etc...

I think you are missing the point John, you never have to prove you have
no bugs!  If the program works all the time and never fails, it is bug free.
A bug is something that causes a program to act in a way it is not designed,
if it always works as designed, it is bug free.  I don't have to prove that.  If
my users are using the program, and there are never any errors produced,
it is by definition bug free.  As I said, the proof is in the pudding.

Nothing in this world can be proven absolutely.  Absolutely nothing.

Regards,

Jim Langston

John Earl wrote:

> <SNIP>
> How do you do that?  (seriously).   How do you "make sure"
> without proving?
>
> I think that you're missing the point here Jim (and it's a
> _very_ important one).  You can't ever prove (or even "make
> sure") a program is bug free.  You can only prove a program
> has bugs.... or fail to prove that it has bugs (which would
> be a good thing).

<SNIP>

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