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< title > The MPL Reference Manual: iterator_category< / title >
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< table class = "header" > < tr class = "header" > < td class = "header-group navigation-bar" > < span class = "navigation-group" > < a href = "./deref.html" class = "navigation-link" > Prev< / a > < a href = "./algorithms.html" class = "navigation-link" > Next< / a > < / span > < span class = "navigation-group-separator" > | < / span > < span class = "navigation-group" > < a href = "./deref.html" class = "navigation-link" > Back< / a > Along< / span > < span class = "navigation-group-separator" > | < / span > < span class = "navigation-group" > < a href = "./iterator-metafunctions.html" class = "navigation-link" > Up< / a > < a href = "../refmanual.html" class = "navigation-link" > Home< / a > < / span > < span class = "navigation-group-separator" > | < / span > < span class = "navigation-group" > < a href = "./refmanual_toc.html" class = "navigation-link" > Full TOC< / a > < / span > < / td >
< td class = "header-group page-location" > < a href = "../refmanual.html" class = "navigation-link" > Front Page< / a > / < a href = "./iterators.html" class = "navigation-link" > Iterators< / a > / < a href = "./iterator-metafunctions.html" class = "navigation-link" > Iterator Metafunctions< / a > / < a href = "./iterator-category.html" class = "navigation-link" > iterator_category< / a > < / td >
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< div class = "section" id = "iterator-category" >
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< h1 > < a class = "toc-backref" href = "./iterator-metafunctions.html#id1459" > iterator_category< / a > < / h1 >
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< h3 > < a class = "subsection-title" href = "#synopsis" name = "synopsis" > Synopsis< / a > < / h3 >
< pre class = "literal-block" >
template<
typename Iterator
>
struct < a href = "./iterator-category.html" class = "identifier" > iterator_category< / a >
{
typedef typename Iterator::category type;
};
< / pre >
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< h3 > < a class = "subsection-title" href = "#description" name = "description" > Description< / a > < / h3 >
< p > Returns one of the following iterator category tags:< / p >
< ul class = "simple" >
< li > < tt class = "literal" > < span class = "pre" > forward_iterator_tag< / span > < / tt > < / li >
< li > < tt class = "literal" > < span class = "pre" > bidirectional_iterator_tag< / span > < / tt > < / li >
< li > < tt class = "literal" > < span class = "pre" > random_access_iterator_tag< / span > < / tt > < / li >
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< / div >
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< h3 > < a class = "subsection-title" href = "#header" name = "header" > Header< / a > < / h3 >
< pre class = "literal-block" >
#include < < a href = "../../../../boost/mpl/iterator_category.hpp" class = "header" > boost/mpl/iterator_category.hpp< / a > >
#include < < a href = "../../../../boost/mpl/iterator_tags.hpp" class = "header" > boost/mpl/iterator_tags.hpp< / a > >
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< h3 > < a class = "subsection-title" href = "#parameters" name = "parameters" > Parameters< / a > < / h3 >
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< colgroup >
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< tr > < th class = "head" > Parameter< / th >
< th class = "head" > Requirement< / th >
< th class = "head" > Description< / th >
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< / tr >
< / thead >
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< tr > < td > < tt class = "literal" > < span class = "pre" > Iterator< / span > < / tt > < / td >
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< td > < a class = "reference internal" href = "./forward-iterator.html" > Forward Iterator< / a > < / td >
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< td > The iterator to obtain a category for.< / td >
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< div class = "section" id = "id449" >
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< h3 > < a class = "subsection-title" href = "#expression-semantics" name = "expression-semantics" > Expression semantics< / a > < / h3 >
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< p > For any < a class = "reference internal" href = "./forward-iterator.html" > Forward Iterator< / a > s < tt class = "literal" > < span class = "pre" > iter< / span > < / tt > :< / p >
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< pre class = "literal-block" >
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typedef < a href = "./iterator-category.html" class = "identifier" > iterator_category< / a > < iter> ::type tag;
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< / pre >
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< table class = "docutils field-list" frame = "void" rules = "none" >
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< col class = "field-name" / >
< col class = "field-body" / >
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< tr class = "field" > < th class = "field-name" > Return type:< / th > < td class = "field-body" > < p class = "first" > < a class = "reference internal" href = "./integral-constant.html" > Integral Constant< / a > .< / p >
< / td >
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< / tr >
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< tr class = "field" > < th class = "field-name" > Semantics:< / th > < td class = "field-body" > < p class = "first" > < tt class = "literal" > < span class = "pre" > tag< / span > < / tt > is < tt class = "literal" > < span class = "pre" > forward_iterator_tag< / span > < / tt > if < tt class = "literal" > < span class = "pre" > iter< / span > < / tt > is a model of < a class = "reference internal" href = "./forward-iterator.html" > Forward Iterator< / a > ,
< tt class = "literal" > < span class = "pre" > bidirectional_iterator_tag< / span > < / tt > if < tt class = "literal" > < span class = "pre" > iter< / span > < / tt > is a model of < a class = "reference internal" href = "./bidirectional-iterator.html" > Bidirectional Iterator< / a > ,
or < tt class = "literal" > < span class = "pre" > random_access_iterator_tag< / span > < / tt > if < tt class = "literal" > < span class = "pre" > iter< / span > < / tt > is a model of < a class = "reference internal" href = "./random-access-iterator.html" > Random Access Iterator< / a > ;< / p >
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< / tr >
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< tr class = "field" > < th class = "field-name" > Postcondition:< / th > < td class = "field-body" > < dl class = "first last docutils" >
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< dt > < tt class = "literal" > < span class = "pre" > forward_iterator_tag::value< / span > < span class = "pre" > < < / span > < span class = "pre" > bidirectional_iterator_tag::value< / span > < / tt > ,< / dt >
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< dd > < p class = "first last" > < tt class = "literal" > < span class = "pre" > bidirectional_iterator_tag::value< / span > < span class = "pre" > < < / span > < span class = "pre" > random_access_iterator_tag::value< / span > < / tt > .< / p >
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< h3 > < a class = "subsection-title" href = "#complexity" name = "complexity" > Complexity< / a > < / h3 >
< p > Amortized constant time.< / p >
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< h3 > < a class = "subsection-title" href = "#example" name = "example" > Example< / a > < / h3 >
< pre class = "literal-block" >
template< typename Tag, typename Iterator >
struct algorithm_impl
{
// < em > O(n)< / em > implementation
};
template< typename Iterator >
struct algorithm_impl< random_access_iterator_tag,Iterator>
{
// < em > O(1)< / em > implementation
};
template< typename Iterator >
struct algorithm
: algorithm_impl<
< a href = "./iterator-category.html" class = "identifier" > iterator_category< / a > < Iterator> ::type
, Iterator
>
{
};
< / pre >
< / div >
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< div class = "section" id = "id452" >
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< h3 > < a class = "subsection-title" href = "#see-also" name = "see-also" > See also< / a > < / h3 >
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< p > < a class = "reference internal" href = "./iterators.html" > Iterators< / a > , < a class = "reference internal" href = "./begin.html" > begin< / a > / < a class = "reference internal" href = "./end.html" > end< / a > , < a class = "reference internal" href = "./advance.html" > advance< / a > , < a class = "reference internal" href = "./distance.html" > distance< / a > , < a class = "reference internal" href = "./next.html" > next< / a > < / p >
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< td > < div class = "copyright-footer" > < div class = "copyright" > Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams< / div >
Distributed under the Boost Software License, Version 1.0. (See accompanying
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