Re: [alg.equal]: really requires a bidirectional iterator

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From	Pete Becker<pete@versatilecoding.com>
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Subject	Re: [alg.equal]: really requires a bidirectional iterator
Date	Sat, 3 Sep 2011 14:36:27 -0700 (PDT)
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On 2011-09-02 17:45:58 +0000, Krzysztof Żelechowski said:

>  The expression (*i == *(first2 + (i - first1))) does not have a meaning for
>  input iterators.

See [alg.general]/12:

	In the description of the algorithms operators + and - are used for some
	of the iterator categories for which they do not have to be defined. In these
	cases the semantics of a+n is the same as that of

		X tmp = a;
  		advance(tmp, n);
  		return tmp;

	and that of b-a is the same as of

		return distance(a, b);

-- 
  Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)


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Thread

[alg.equal]: really requires a bidirectional iterator Krzysztof Żelechowski<giecrilj@stegny.2a.pl> - 2011-09-02 10:45 -0700
  Re: [alg.equal]: really requires a bidirectional iterator Daniel Krügler<daniel.kruegler@googlemail.com> - 2011-09-03 14:36 -0700
  Re: [alg.equal]: really requires a bidirectional iterator Pete Becker<pete@versatilecoding.com> - 2011-09-03 14:36 -0700
    Re: [alg.equal]: really requires a bidirectional iterator Krzysztof Żelechowski<giecrilj@stegny.2a.pl> - 2011-09-05 15:13 -0700
      Re: [alg.equal]: really requires a bidirectional iterator Daniel Krügler<daniel.kruegler@googlemail.com> - 2011-09-06 11:19 -0700
  Re: [alg.equal]: really requires a bidirectional iterator Dave Abrahams<dave@boostpro.com> - 2011-09-03 14:36 -0700

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