Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!mintaka!wald
From: wald@theory.lcs.mit.edu (David Wald)
Newsgroups: comp.lang.c
Subject: Re: Is something wrong with the compiler ?
Message-ID: <1990Oct6.194120.27656@mintaka.lcs.mit.edu>
Date: 6 Oct 90 19:41:20 GMT
References: <1895@tuvie> <645@demott.COM> <1903@tuvie> <26875@mimsy.umd.edu>
Sender: daemon@mintaka.lcs.mit.edu (Lucifer Maleficius)
Reply-To: wald@theory.lcs.mit.edu (David Wald)
Organization: Laboratory for Computer Science, MIT
Lines: 35

In article <26875@mimsy.umd.edu> chris@mimsy.umd.edu (Chris Torek) writes:
>In short, when the ANSI standard says that the result of an operation
>is undefined, it means UNDEFINED.  The computer can do anything (like
>turn into a flower)---the system does not have to do anything remotely
>reasonable.

I'm continually amused by the examples people give for undefined and
implementation-defined behavior.  Can we get a list together, possibly
to be incorporated into an Emacs macro?

Examples:

  Melt your screen;
  Call your mother;
  Send nasty notes to your boss;
  ...?


-David


``The `#pragma' command is specified in the ANSI standard to have an
arbitrary implementation-defined effect.  In the GNU C preprocessor,
`#pragma' first attempts to run the game `rogue';  if that fails, it
tries to run the game `hack'; if that fails, it tries to run GNU Emacs
displaying the Tower of Hanoi; if that fails, it reports a fatal
error.  In any case, preprocessing does not continue.''
       -- from the manual for the GCC preprocessor (GCC version 1.34)



--
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David Wald                                           wald@theory.lcs.mit.edu
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