In article <53bru3$2ls@decaxp.harvard.edu> ccshan@husc.harvard.edu
(Chung-chieh Shan) writes:

|> I'm wondering about the non-const version of string::operator[]
|> (size_t pos) (or rather, basic_string<...>::operator[](size_t pos)).
|> In the April DWP (lib.string.access or 21.1.1.7), this is defined to
|> return data()[pos], but data() itself is defined to return a const
|> char *.  No const_cast is present to cast the const char * returned
|> by data() into a char * instead (so that the non-const version of
|> operator[] can return a non-const char &).  Am I missing something
|> here, or will this be fixed in a future version?

I think that this is an error.  If I understand correctly, there is no
constraint that the characters be store in adjacent memory in the
internal representation of the string.

|> Since operator[] can return a non-const char &, though, I wonder if
|> it is portable to write code that modifies not just the char
|> referenced to by the return value of operator[], but also adjacent
|> chars.  For example, if "str" is a string, is it ok to pass &(str[0])
|> to the Unix low-level write() system call (having appropriately
|> resized str before the call)?

It is OK to pass it to write() if and only if the number of characters
read <= 1.  As above, I do not believe that there is any constraint that
the characters be stored in contiguous memory.  (Note, for example, that
the type of the iterator is implementation defined.)
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Hello,

I'm wondering about the non-const version of string::operator[]
(size_t pos) (or rather, basic_string<...>::operator[](size_t pos)).
In the April DWP (lib.string.access or 21.1.1.7), this is defined to
return data()[pos], but data() itself is defined to return a const
char *.  No const_cast is present to cast the const char * returned
by data() into a char * instead (so that the non-const version of
operator[] can return a non-const char &).  Am I missing something
here, or will this be fixed in a future version?

Since operator[] can return a non-const char &, though, I wonder if
it is portable to write code that modifies not just the char
referenced to by the return value of operator[], but also adjacent
chars.  For example, if "str" is a string, is it ok to pass &(str[0])
to the Unix low-level write() system call (having appropriately
resized str before the call)?

Thanks in advance for your help...

--
blue | Chung-chieh Shan (Ken) | Life is a sexually transmitted
 ()  | ccshan@fas.harvard.edu |      math too is a terminal representation
 /\  | Finger for PGP key     |      game.         disease. of Quality.
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