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From: Ludovic Brenta <ludovic@ludovic-brenta.org>
Newsgroups: comp.lang.ada
Subject: Re: A curiosity...
Date: Thu, 4 Dec 2008 14:04:28 -0800 (PST)
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Date: 2008-12-04T14:04:28-08:00
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On Dec 4, 10:48 pm, Hyman Rosen <hyro...@mail.com> wrote:
> Adam Beneschan wrote:
> > Ahhh, sanity at last...
>
> In fact, that "chilling" code wasn't really bad. It's just that
> pthread_create gets a void * final parameter which it passes along
> as an argument to the thread function it starts. The tutorial code
> wants to pass in a plain integer, so it casts the integer into a
> pointer so that it can pass it to pthread_create and then the thread
> routine casts it back to an integer.
>
> On any conventional architecture, casting a small integer to pointer
> and back will leave its value unchanged, and the ability to do this
> very common in C compilers and has been for decades.

Yes. In fact, C requires that pointers and integers be interchangable
so as to make address arithmetic "transparent" and extremely
dangerous. That's why, instead of writing "&th[t]" as Adam did, they
wrote "th+t" and thought themselves clever.

I'm glad I no longer program in C or C++.

--
Ludovic Brenta.