Re: computer language used to program Mars Lander

[Maciej Sobczak <see.my.homepage@gmail.com>]

On 14 Lip, 13:49, Nick Keighley <nick_keighley_nos...@hotmail.com>
wrote:

> I suspect its a damn sight easier to prove C correct than C++.
>
>     a = b + c;
>
> probably does what it says in C (assuming b and c have good values
> and it doesn't overflow). In C++ there could be half a dozen
> overloaded
> operators in there.

Your reasoning is completely broken.
Let's try this one:

I suspect its a damn sight easier to prove C correct than Ada.

a = b + c;

probably does what it says in C. In Ada (substitute := for = ) there
could be half a dozen overloaded operators in there (and some
controlled operations as well).

Do you think that there are some monkeys in the project that randomly
overload operators? If yes, then Ada is equally vulnerable.

Another point: the operator + in C *is* overloaded and not only its
meaning, but also the generated object code differs depending on the
types of a and b. Yes, this is what overloading is all about and yes,
you can have serious errors in C because of that, especially when
combined with implicit conversions. What C++ or Ada can offer in this
area is at least to get rid of those implicit conversions. This is a
huge gain for proving correctness of the code.

--
Maciej Sobczak * www.msobczak.com * www.inspirel.com