I have a large char[] which I'd like to copy a portion of into a
vector<char>. I can't seem to locate a simple method for doing so. I
assume involving iterators will not result in memcpy not being used
and therefore will be less than optimal. Can anyone help me out?
Regards,
Steven
5  1891 
On 5 Feb 2004 21:28:39 -0800, sm*@essemer.com .au (Steven Reddie) wrote: I have a large char[] which I'd like to copy a portion of into a
vector<char> . I can't seem to locate a simple method for doing so. I
assume involving iterators will not result in memcpy not being used
and therefore will be less than optimal. Can anyone help me out?
Check the std::vector constructors for constructing a vector from a
character array.
Check the resizing member functions and std::copy for copying into
an existing vector.
"Steven Reddie" <sm*@essemer.co m.au> wrote in message
news:f9******** *************** ***@posting.goo gle.com... I have a large char[] which I'd like to copy a portion of into a
vector<char>. I can't seem to locate a simple method for doing so.
I assume involving iterators will not result in memcpy not being used
and therefore will be less than optimal. Can anyone help me out?
A good implementation of std::copy will use memcpy, memmove or
something similar in the case you describe. You could also use
char_traits<cha r>::copy.
Jonathan
On 5 Feb 2004 21:28:39 -0800, sm*@essemer.com .au (Steven Reddie)
wrote: I have a large char[] which I'd like to copy a portion of into a
vector<char> . I can't seem to locate a simple method for doing so. I
assume involving iterators will not result in memcpy not being used
and therefore will be less than optimal. Can anyone help me out?
std::vector<cha r> v(chararray, chararray + sizeof(chararra y));
will collapse to a memcpy or memmove call on most (all?) vector
implementations I know of. Trace in with a debugger to confirm.
Tom
C++ FAQ: http://www.parashift.com/c++-faq-lite/
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
tom_usenet <to********@hot mail.com> wrote in message news:<gk******* *************** **********@4ax. com>... On 5 Feb 2004 21:28:39 -0800, sm*@essemer.com .au (Steven Reddie)
wrote:
std::vector<cha r> v(chararray, chararray + sizeof(chararra y));
will collapse to a memcpy or memmove call on most (all?) vector
implementations I know of. Trace in with a debugger to confirm.
Thanks guys. It looks like I'm misreading the docs. This last form
of constructor must be the one defined as:
template<class InputIterator> vector(InputIte rator _First,
InputIterator _Last);
which implies that InputIterator for a vector<char> is or is
implicitly constructed from a char*. It's been a while since I've
used the STL that it seems that I'm forgetting some really basic
stuff.
Regards,
Steven
On 6 Feb 2004 19:14:52 -0800, sm*@essemer.com .au (Steven Reddie)
wrote: tom_usenet <to********@hot mail.com> wrote in message news:<gk******* *************** **********@4ax. com>... On 5 Feb 2004 21:28:39 -0800, sm*@essemer.com .au (Steven Reddie)
wrote:
std::vector<cha r> v(chararray, chararray + sizeof(chararra y));
will collapse to a memcpy or memmove call on most (all?) vector
implementations I know of. Trace in with a debugger to confirm.
Thanks guys. It looks like I'm misreading the docs. This last form
of constructor must be the one defined as:
template<cla ss InputIterator> vector(InputIte rator _First,
InputIterato r _Last);
which implies that InputIterator for a vector<char> is or is
implicitly constructed from a char*.
That constructor is the one that matches. You end up calling:
vector<char>::v ector<char*>(ch ar* _First, char* _Last);
That templated constructor should dispatch to a memmove/memcpy
implementation, since char is a scalar and char* is a simple pointer
or the same type.
Tom
C++ FAQ: http://www.parashift.com/c++-faq-lite/
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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