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Re: confusion about behavior

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On Sun, 14 Aug 2011 15:10:48 -0400, James Kuyper wrote:

> On 08/14/2011 02:56 PM, LJ wrote:
>> int     a = 2;
>> int     b = 3;
>> c = a+++b;
>> What will be the value of c??
>> Shouldn't it be undefined depending upon the interpretation??
> 
> The C standard mandates what's called the "maximal munch" rule; "If the
> input stream has been parsed into preprocessing tokens up to a given
> character, the next preprocessing token is the longest sequence of
> characters that could constitute a preprocessing token." (6.4p4)
> 
> Therefore, there's only one permitted way of parsing the third
> statement:
> 
> 	c = a++ + b;
> 
> That's equivalent to the following statement, where I've inserted some
> unnecessary parenthesis to clarify the order of operations:
> 
> 	c = ((a++) + b);
> 
> Assuming that c has an arithmetic type, the behavior of that statement
> is well-defined: 'a' ends up with a value of 3, and c ends up with a
> value of 5 (converted, if necessary, to whatever the type of c happens
> to be).

So, c would actually be equal to 6. :)

c = ((a++) + b)
c = ((2++) + 3)
c = (3 + 3)
c = 6

I never heard of the "maximal munch" thing. Thanks for the explanation.

Todd

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confusion about behavior LJ <djtheshowstopper@gmail.com> - 2011-08-14 11:56 -0700
  Re: confusion about behavior China Blue Tip Wrench <chine.bleu@yahoo.com> - 2011-08-14 12:05 -0700
  Re: confusion about behavior Keith Thompson <kst-u@mib.org> - 2011-08-14 12:06 -0700
    Re: confusion about behavior Todd Carnes <toddcarnes@gmail.com> - 2011-08-15 01:57 +0000
      Re: confusion about behavior Keith Thompson <kst-u@mib.org> - 2011-08-14 19:10 -0700
        Re: confusion about behavior Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-08-15 03:44 +0100
          Re: confusion about behavior Keith Thompson <kst-u@mib.org> - 2011-08-14 20:27 -0700
      Re: confusion about behavior Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-14 22:52 -0400
      Re: confusion about behavior Seebs <usenet-nospam@seebs.net> - 2011-08-15 04:28 +0000
        Re: confusion about behavior Kenneth Brody <kenbrody@spamcop.net> - 2011-08-15 15:31 -0400
          Re: confusion about behavior Keith Thompson <kst-u@mib.org> - 2011-08-15 12:36 -0700
          Re: confusion about behavior Seebs <usenet-nospam@seebs.net> - 2011-08-15 20:33 +0000
            Re: confusion about behavior Kenneth Brody <kenbrody@spamcop.net> - 2011-08-16 14:39 -0400
              Re: confusion about behavior Keith Thompson <kst-u@mib.org> - 2011-08-16 12:27 -0700
                Re: confusion about behavior Willem <willem@toad.stack.nl> - 2011-08-16 19:47 +0000
      Re: confusion about behavior Barry Schwarz <schwarz45@yahoo.com> - 2011-09-05 04:50 -0700
        [OT] Re: confusion about behavior Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-05 09:07 -0400
        Re: confusion about behavior Kenneth Brody <kenbrody@spamcop.net> - 2011-09-06 12:42 -0400
  Re: confusion about behavior James Kuyper <jameskuyper@verizon.net> - 2011-08-14 15:10 -0400
    Re: confusion about behavior Todd Carnes <toddcarnes@gmail.com> - 2011-08-15 02:04 +0000
      Re: confusion about behavior Keith Thompson <kst-u@mib.org> - 2011-08-14 19:15 -0700
        Re: confusion about behavior Todd Carnes <toddcarnes@gmail.com> - 2011-08-15 02:34 +0000
      Re: confusion about behavior James Kuyper <jameskuyper@verizon.net> - 2011-08-14 22:37 -0400
    Re: confusion about behavior Todd Carnes <toddcarnes@gmail.com> - 2011-08-15 02:26 +0000

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