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Date: Wed, 19 Jun 91 23:20:09 -0400
From: karl@grebyn.com (Karl A. Nyberg)
Subject: Why C is hard to learn - Was: Is it a bug in C compilers?
Message-ID: <9106200320.AA00393@grebyn.com>
List-Id: <comp.lang.ada>

[Forwarded from alt.sys.sun (of all places)]

Does C++ inherit (!) this (mis?)feature from C?  And we thought the Ada
lawyers had a monopoly on quoting the Language Reference Manual!

-- Karl --

In article <4201@island.COM> rich@island.COM writes:
>luke@research.canon.oz.au (Luke Kendall) writes:
>>A bug in the Sun and GNU C compilers.  The following tiny program does
>>not work:
>
>>main()
>>{
>>    int		i, shift;
>>    printf("%x\n", 0x10000 >> 1000);
>>    for (shift = 1, i = 0; i < 5; ++i, shift *= 10)
>>	printf("%x >> %d = %x\n", 0x10000, shift, 0x10000 >> shift);
>>}


>>From The C Programming Language, Second Edition, by Kernighan and Ritchie,
>pg. 206, on the right shift operator:
>
>"The result is undefined if the right operand is negative, or greater than
>or equal to the number of bits in the left expression's type."
>
>>In other words, both compilers are failing to mask the right operand
>>of the shift.
>
>Failing, yes, but then the language definition explicitly states that 
>the compiler does not have to handle this case.  This is yet another
>reason why C is one of the most efficient high-level languages and hard
>for programmers to master.