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Extensions
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< / th > < td width = "20%" align = "right" > < a accesskey = "n" href = "ext_sgi.html" > Next< / a > < / td > < / tr > < / table > < hr / > < / div > < div class = "chapter" > < div class = "titlepage" > < div > < div > < h2 class = "title" > < a id = "manual.ext.containers" > < / a > Chapter < / h2 > < / div > < / div > < / div > < div class = "toc" > < p > < strong > Table of Contents< / strong > < / p > < dl class = "toc" > < dt > < span class = "section" > < a href = "ext_containers.html#manual.ext.containers.sgi" > Backwards Compatibility< / a > < / span > < / dt > < dt > < span class = "section" > < a href = "ext_sgi.html" > Deprecated< / a > < / span > < / dt > < / dl > < / div > < div class = "section" > < div class = "titlepage" > < div > < div > < h2 class = "title" style = "clear: both" > < a id = "manual.ext.containers.sgi" > < / a > Backwards Compatibility< / h2 > < / div > < / div > < / div > < p > A few extensions and nods to backwards-compatibility have
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been made with containers. Those dealing with older SGI-style
allocators are dealt with elsewhere. The remaining ones all deal
with bits:
< / p > < p > The old pre-standard < code class = "code" > bit_vector< / code > class is
present for backwards compatibility. It is simply a typedef for
the < code class = "code" > vector< bool> < / code > specialization.
< / p > < p > The < code class = "code" > bitset< / code > class has a number of extensions, described in the
rest of this item. First, we'll mention that this implementation of
< code class = "code" > bitset< N> < / code > is specialized for cases where N number of
bits will fit into a single word of storage. If your choice of N is
within that range (< =32 on i686-pc-linux-gnu, for example), then all
of the operations will be faster.
< / p > < p > There are
versions of single-bit test, set, reset, and flip member functions which
do no range-checking. If we call them member functions of an instantiation
of < code class = "code" > bitset< N> < / code > , then their names and signatures are:
< / p > < pre class = "programlisting" >
bitset< N> & _Unchecked_set (size_t pos);
bitset< N> & _Unchecked_set (size_t pos, int val);
bitset< N> & _Unchecked_reset (size_t pos);
bitset< N> & _Unchecked_flip (size_t pos);
bool _Unchecked_test (size_t pos);
< / pre > < p > Note that these may in fact be removed in the future, although we have
no present plans to do so (and there doesn't seem to be any immediate
reason to).
< / p > < p > The member function < code class = "code" > operator[]< / code > on a const bitset returns
a bool, and for a non-const bitset returns a < code class = "code" > reference< / code > (a
nested type). No range-checking is done on the index argument, in keeping
with other containers' < code class = "code" > operator[]< / code > requirements.
< / p > < p > Finally, two additional searching functions have been added. They return
the index of the first "on" bit, and the index of the first
"on" bit that is after < code class = "code" > prev< / code > , respectively:
< / p > < pre class = "programlisting" >
size_t _Find_first() const;
size_t _Find_next (size_t prev) const;< / pre > < p > The same caveat given for the _Unchecked_* functions applies here also.
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