back_inserter() on strings

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  • Joe Laughlin
    #1

    back_inserter() on strings

    Joe Laughlin wrote:[color=blue]
    > Mike Wahler wrote:[color=green]
    >> "Joe Laughlin" <Joseph.V.Laugh lin@boeing.com> wrote in
    >> message news:I60Dvs.FqL @news.boeing.co m...[/color][/color]
    <snip>[color=blue][color=green][color=darkred]
    >>> Joe Laughlin wrote:
    >>> std::back_inser t_iterator<std: :string>::opera tor=(const
    >>> std::back_inser t_iterator<std: :string>&)[/color]
    >>
    >> 'back_insert_it erator' requires that the container type
    >> specified by its template argument defines members
    >> 'push_back()' and 'value_type'. 'std::string' defines the
    >> latter, but not the former.
    >>
    >> IOW you cannot use 'back_insert_it erator' with a
    >> 'std::string'. ('std::string', while sharing much
    >> commonality with them, isn't strictly a 'container').
    >>
    >> -Mike[/color]
    >
    > Argh.
    >
    > From "Accelerate d C++", pg 121:
    >
    > "back_inserter( c)
    > Yields an iterator on the container c that appends
    > elements to c. The container must support push_back,
    > which the list, vector, and the string types all do."[/color]

    Was the book wrong? Or am I reading it wrong?


    Tags: None
    • Victor Bazarov
      #2
      Re: back_inserter() on strings

      Joe Laughlin wrote:[color=blue]
      > Joe Laughlin wrote:[color=green]
      >>Mike Wahler wrote:[color=darkred]
      >>>"Joe Laughlin" <Joseph.V.Laugh lin@boeing.com> wrote in
      >>>message news:I60Dvs.FqL @news.boeing.co m...[/color][/color]
      >
      > <snip>
      >[color=green][color=darkred]
      >>>>Joe Laughlin wrote:
      >>>>std::back_i nsert_iterator< std::string>::o perator=(const
      >>>>std::back_i nsert_iterator< std::string>&)
      >>>
      >>>'back_insert _iterator' requires that the container type
      >>>specified by its template argument defines members
      >>>'push_back() ' and 'value_type'. 'std::string' defines the
      >>>latter, but not the former.
      >>>
      >>>IOW you cannot use 'back_insert_it erator' with a
      >>>'std::string '. ('std::string', while sharing much
      >>> commonality with them, isn't strictly a 'container').
      >>>
      >>>-Mike[/color]
      >>
      >>Argh.
      >>
      >>From "Accelerate d C++", pg 121:
      >>
      >>"back_inserte r(c)
      >> Yields an iterator on the container c that appends
      >>elements to c. The container must support push_back,
      >>which the list, vector, and the string types all do."[/color]
      >
      >
      > Was the book wrong? Or am I reading it wrong?[/color]

      I can't attest to your reading of it, but the book is not wrong.

      From the Standard, 21.3/2:
      "The template class basic_string conforms to the requirements of
      a Sequence, as specified in (23.1.1). Additionally, because the
      iterators supported by basic_string are random access iterators
      (24.1.5), basic_string conforms to the the requirements of
      a Reversible Container, as specified in (23.1)."

      IOW, a string _is_ a sequential container, no matter how much Mike may
      want to make it sound that it isn't. Whatever _conforms_ to the
      requirements for a container _is_ a container, as far as C++ is concerned.

      V

        Comment

        • Tom Widmer
          #3
          Re: back_inserter() on strings

          On Tue, 26 Oct 2004 17:50:02 GMT, "Joe Laughlin"
          <Joseph.V.Laugh lin@boeing.com> wrote:
          [color=blue]
          >Joe Laughlin wrote:[color=green]
          >> Mike Wahler wrote:[color=darkred]
          >>> "Joe Laughlin" <Joseph.V.Laugh lin@boeing.com> wrote in
          >>> message news:I60Dvs.FqL @news.boeing.co m...[/color][/color]
          ><snip>[color=green][color=darkred]
          >>>> Joe Laughlin wrote:
          >>>> std::back_inser t_iterator<std: :string>::opera tor=(const
          >>>> std::back_inser t_iterator<std: :string>&)
          >>>
          >>> 'back_insert_it erator' requires that the container type
          >>> specified by its template argument defines members
          >>> 'push_back()' and 'value_type'. 'std::string' defines the
          >>> latter, but not the former.
          >>>
          >>> IOW you cannot use 'back_insert_it erator' with a
          >>> 'std::string'. ('std::string', while sharing much
          >>> commonality with them, isn't strictly a 'container').
          >>>
          >>> -Mike[/color]
          >>
          >> Argh.
          >>
          >> From "Accelerate d C++", pg 121:
          >>
          >> "back_inserter( c)
          >> Yields an iterator on the container c that appends
          >> elements to c. The container must support push_back,
          >> which the list, vector, and the string types all do."[/color]
          >
          >Was the book wrong? Or am I reading it wrong?[/color]

          The book is right - std::basic_stri ng::push_back is standard. However,
          VC6 has a pre-standard library in which std::string::pu sh_back is not
          present, which might be the source of the confusion.

          Tom

            Comment

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