back_inserter() on strings

[Joe Laughlin]

Joe Laughlin wrote:

Mike Wahler wrote:

"Joe Laughlin" <Jo***************@boeing.com> wrote in
message news:I6********@news.boeing.com... <snip>

Joe Laughlin wrote:
std::back_insert_iterator<std::string>::operator=( const
std::back_insert_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_iterator' with a
'std::string'. ('std::string', while sharing much
commonality with them, isn't strictly a 'container').

-Mike

Argh.

From "Accelerated 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."

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

[Victor Bazarov]

Joe Laughlin wrote:

Joe Laughlin wrote:

Mike Wahler wrote:

"Joe Laughlin" <Jo***************@boeing.com> wrote in
message news:I6********@news.boeing.com...
<snip>
Joe Laughlin wrote:
std::back_insert_iterator<std::string>::operat or=(const
std::back_insert_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_iterator' with a
'std::string'. ('std::string', while sharing much
commonality with them, isn't strictly a 'container').

-Mike

Argh.

From "Accelerated 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."

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

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

[Tom Widmer]

On Tue, 26 Oct 2004 17:50:02 GMT, "Joe Laughlin"
<Jo***************@boeing.com> wrote:

Joe Laughlin wrote:

Mike Wahler wrote:

"Joe Laughlin" <Jo***************@boeing.com> wrote in
message news:I6********@news.boeing.com...<snip> Joe Laughlin wrote:
std::back_insert_iterator<std::string>::operator=( const
std::back_insert_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_iterator' with a
'std::string'. ('std::string', while sharing much
commonality with them, isn't strictly a 'container').

-Mike

Argh.

From "Accelerated 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."

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

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

Tom