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Groups > comp.lang.c > #21901

Re: Why no warning?

From James Kuyper <jameskuyper@verizon.net>
Newsgroups comp.lang.c
Subject Re: Why no warning?
Date 2012-06-06 08:56 -0400
Organization A noiseless patient Spider
Message-ID <4FCF5382.1040309@verizon.net> (permalink)
References <6d2a019d-fea9-406d-9cda-e0d77566f4e6@googlegroups.com> <c6a8ef9a-d38b-41cd-9bc4-71e21a1c4cad@googlegroups.com>

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On 06/06/2012 07:35 AM, Hill Pang wrote:
> On Wednesday, June 6, 2012 5:42:13 PM UTC+8, Hill Pang wrote:
>> I was expecting a warning for this assignment, but can't get from GCC, why? isn't it an overflow?
>>  
>> char c = 0xff;
> 
> Thanks, every one!
> 
> Yes, with additional options, the warning shows, but for me I think it is straight to check if a const is in the represent-able range of a variable in an assignment, I think the warning should be popped up by default rather by an extra option. I am wondering if there is some special rulers behind this, is there any such ruler listed in the C standard or some place anywhere?

The C standard mandates certain diagnostics. gcc does not provide all of
the mandated diagnostics for any version of the C standard (and is
therefore not a conforming implementation of C) without either the -ansi
or the -std= options, plus -pedantic. There's LOTS of additional useful
warnings not mandated by the C standard, and you need to explicitly
request them; -Wall gets most of the most useful ones. I like to add
-Wpointer-arith -Wcast-align -Wstrict-prototypes -Wmissing-prototypes

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Thread

Why no warning? Hill Pang <pangbw@gmail.com> - 2012-06-06 02:42 -0700
  Re: Why no warning? Noob <root@127.0.0.1> - 2012-06-06 12:04 +0200
    Re: Why no warning? Hill Pang <pangbw@gmail.com> - 2012-06-06 03:17 -0700
      Re: Why no warning? James Kuyper <jameskuyper@verizon.net> - 2012-06-06 06:29 -0400
        Re: Why no warning? Noob <root@127.0.0.1> - 2012-06-06 12:54 +0200
  Re: Why no warning? David Brown <david@westcontrol.removethisbit.com> - 2012-06-06 12:28 +0200
    Re: Why no warning? Noob <root@127.0.0.1> - 2012-06-06 12:55 +0200
      Re: Why no warning? David Brown <david@westcontrol.removethisbit.com> - 2012-06-06 13:17 +0200
  Re: Why no warning? Hill Pang <pangbw@gmail.com> - 2012-06-06 04:35 -0700
    Re: Why no warning? James Kuyper <jameskuyper@verizon.net> - 2012-06-06 08:56 -0400
      Re: Why no warning? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-06-07 15:05 +0000
  Re: Why no warning? China Blue Max <chine.bleu@yahoo.com> - 2012-06-06 04:53 -0700
    Re: Why no warning? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-06-06 13:29 +0100
      Re: Why no warning? Willem <willem@toad.stack.nl> - 2012-06-06 13:07 +0000
        Re: Why no warning? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-06-06 17:37 +0100
  Re: Why no warning? Ralph Spitzner <rasp@spitzner.org> - 2012-06-06 16:57 +0200
    Re: Why no warning? James Kuyper <jameskuyper@verizon.net> - 2012-06-06 11:20 -0400
    Re: Why no warning? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-06-06 17:45 +0100

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