Common way to obfuscate?

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3 total messages Started by Marcel van Kervinck Thu, 11 Apr 1996 00:55

#2571

Author: Marcel van Kervinck
Date: Thu, 11 Apr 1996 00:55

17 lines
718 bytes

I just recovered from a slight shock caused by realizing that
one could legally rewrite

	a[b[c]]

as

	c[b][a]

Is this a common way to obfuscate code?

Regards,
	Marcel
--  _   _
  _| |_|_|
 |_    |_     Marcel van Kervinck
         |_|  buex95a@urc.tue.nl

Re: Common way to obfuscate?

#2568

Author: Tim Hollebeek
Date: Thu, 11 Apr 1996 01:59

15 lines
1185 bytes

Marcel van Kervinck (buex95a@urc.tue.nl) wrote:
: I just recovered from a slight shock caused by realizing that
: one could legally rewrite 'a[b[c]]' as 'c[b][a]'

Right, since they are both *(a + *(b + c)).  Cute.

: Is this a common way to obfuscate code?

Wouldn't know.  I strive to write clear code :-)

---------------------------------------------------------------------------
Tim Hollebeek         | Disclaimer :=> Everything above is a true statement,
Electron Psychologist |                for sufficiently false values of true.
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Re: Common way to obfuscate?

#2596

Author: Nick Maclaren
Date: Mon, 15 Apr 1996 18:08

26 lines
1525 bytes

In article <4khp20$pt@solutions.solon.com>, tim@franck.Princeton.EDU (Tim Hollebeek) writes:
|> Marcel van Kervinck (buex95a@urc.tue.nl) wrote:
|> : I just recovered from a slight shock caused by realizing that
|> : one could legally rewrite 'a[b[c]]' as 'c[b][a]'
|> 
|> Right, since they are both *(a + *(b + c)).  Cute.

This is one of the bizarrer aspects of C's history.  The equivalence
comes from BCPL which, being typeless, a[b] and b[a] (actually a!b
and b!a) were naturally the same.  I have no idea how it survived the
language changes from BCPL to B and then C!

|> : Is this a common way to obfuscate code?
|> 
|> Wouldn't know.  I strive to write clear code :-)

In BCPL, it was quite clear.  I believe that its only use in C is
deliberately to obfuscate code, and I have never seen it used even
in the worst macroid programs.


Nick Maclaren,
University of Cambridge Computer Laboratory,
New Museums Site, Pembroke Street, Cambridge CB2 3QG, England.
Email:  nmm1@cam.ac.uk
Tel.:  +44 1223 334761    Fax:  +44 1223 334679

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