how to initialize an stl iterator in vc2005

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  • thinktwice
    #1

    how to initialize an stl iterator in vc2005

    std::vector<CSt ringvec;
    vec::iterator iter;

    i can initiaze the iterator in vc6 like this $B!'(B iter = NULL, but it
    compile failed in vc2005, it tells me there is no acceptable
    conversion.


    Tags: None
    • Stefan Naewe
      #2
      Re: how to initialize an stl iterator in vc2005

      On 7/1/2008 2:41 PM, thinktwice wrote:
      std::vector<CSt ringvec;
      vec::iterator iter;
      >
      i can initiaze the iterator in vc6 like this ： iter = NULL, but it
      compile failed in vc2005, it tells me there is no acceptable
      conversion.
      How true...
      Repeat after me: "An iterator is not a pointer".

      Try this:


      std::vector<CSt ringvec;
      std::vector<CSt ring>::iterator iter = vec.end();



      What problem do you try to solve?


      Regards,
      Stefan
      --
      Stefan Naewe stefan dot naewe at atlas-elektronik dot com
      Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
      Plain text mails only, please http://www.expita.com/nomime.html

        Comment

        • thinktwice
          #3
          Re: how to initialize an stl iterator in vc2005

          thanks for your reply, i want to use a class data member whhose type
          is a iteraotr, i might use in several class methods, but before use it
          i want to know whether this iterator is null or invalid

          On 7ÔÂ1ÈÕ, ÏÂÎç9ʱ00·Ö, Stefan Naewe <nos...@please. .netwrote:
          On 7/1/2008 2:41 PM, thinktwice wrote:
          >
          std::vector<CSt ringvec;
          vec::iterator iter;
          >
          i can initiaze the iterator in vc6 like this £º iter = NULL, but it
          compile failed in vc2005, it tells me there is no acceptable
          conversion.
          >
          How true...
          Repeat after me: "An iterator is not a pointer".
          >
          Try this:
          >
          std::vector<CSt ringvec;
          std::vector<CSt ring>::iterator iter = vec.end();
          >
          What problem do you try to solve?
          >
          Regards,
          Stefan
          --
          Stefan Naewe stefan dot naewe at atlas-elektronik dot com
          Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
          Plain text mails only, please http://www.expita.com/nomime.html

            Comment

            • Kai-Uwe Bux
              #4
              Re: how to initialize an stl iterator in vc2005

              thinktwice wrote:
              thanks for your reply, i want to use a class data member whhose type
              is a iteraotr, i might use in several class methods, but before use it
              i want to know whether this iterator is null or invalid
              (a) Please don't top-post.

              (b) Generally, it is impossible to determine through inspection whether an
              iterator is invalid. The point is that operations on the underlying
              container can invalidate iterators. The iterator is not required to detect
              that.

              (c) With a lot of care, you could use the container.end() value to indicate
              an invalid iterator. However, this is fragile because of the problems
              mentioned in (b).

              (d) It might be better to consider a redesign that avoids the need for
              checking the validity of the iterator. What is the underlying problem you
              are trying to solve?


              Best

              Kai-Uwe Bux
              On 7?1?, ??9?00?, Stefan Naewe <nos...@please. netwrote:
              >On 7/1/2008 2:41 PM, thinktwice wrote:
              >>
              std::vector<CSt ringvec;
              vec::iterator iter;
              >>
              i can initiaze the iterator in vc6 like this ? iter = NULL, but it
              compile failed in vc2005, it tells me there is no acceptable
              conversion.
              >>
              >How true...
              >Repeat after me: "An iterator is not a pointer".
              >>
              >Try this:
              >>
              >std::vector<CS tringvec;
              >std::vector<CS tring>::iterato r iter = vec.end();
              >>
              >What problem do you try to solve?
              >>
              >Regards,
              > Stefan
              >--
              >Stefan Naewe stefan dot naewe at atlas-elektronik dot com
              >Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
              >Plain text mails only, please http://www.expita.com/nomime.html
              PS: also please don't quote signatures.

                Comment

                • James Kanze
                  #5
                  Re: how to initialize an stl iterator in vc2005

                  On Jul 1, 2:41 pm, thinktwice <memorial...@gm ail.comwrote:
                  std::vector<CSt ringvec;
                  vec::iterator iter;
                  i can initiaze the iterator in vc6 like this ? iter = NULL, but it
                  compile failed in vc2005, it tells me there is no acceptable
                  conversion.
                  It's undefined behavior. VC 6.0 failed to tell you about the
                  error; later versions do.

                  --
                  James Kanze (GABI Software) email:james.kan ze@gmail.com
                  Conseils en informatique orientée objet/
                  Beratung in objektorientier ter Datenverarbeitu ng
                  9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34

                    Comment

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