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< html >< head >< title > boost::mpl::count</ title >
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< h1 >< a href = "../Table_of_Contents.html" >< img src = "../mpl_logo.jpg" alt = "[Home]" border = 0 align = "right" ></ a > count</ h1 >< h3 > Synopsis</ h3 >
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< p >
< pre >
template<
typename Sequence
, typename T
>
struct count
{
typedef < em > unspecified</ em > type;
};
</ pre >
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< h3 > Description</ h3 >
< p >
Returns the number of elements in a < code > Sequence</ code > that are identical to < code > T</ code > .
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< h3 > Definition</ h3 >
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< pre >
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#include "< a href = "../../../../../boost/mpl/count.hpp" > boost/mpl/count.hpp</ a > "
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</ pre >
< p >
< h3 > Parameters</ h3 >
< table border = "1" >
< tr >< th > Parameter </ th >< th > Requirement </ th >< th > Description </ th ></ tr >
< tr >< td >< code > Sequence</ code ></ td >< td > A model of < a href = "../Forward_Sequence.html" > Forward Sequence</ a ></ td >< td > A sequence to be examined. </ td ></ tr >
< tr >< td >< code > T</ code ></ td >< td > A type</ td >< td > The type to be searched for. </ td ></ tr >
</ table >
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< h3 > Expression semantics</ h3 >
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< table border = "1" >
< tr >< th > Expression </ th >< th > Expression type </ th >< th > Precondition </ th >< th > Semantics </ th >< th > Postcondition </ th ></ tr >
< tr >< td >< code > typedef count< Sequence,T> ::type n;</ code ></ td >< td > A model of < a href = "../Integral_Constant.html" > Integral Constant</ a ></ td >< td ></ td >< td > Equivalent to < code > typedef < a href = "../Reference/count_if.html" > count_if</ a > < Sequence,is_same< _,T> > ::type n;</ code ></ td >< td ></ td ></ tr >
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< h3 > Complexity</ h3 >
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Linear. Exactly < code >< a href = "../Reference/size.html" > size</ a > < Sequence> ::value</ code > comparisons for identity.
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< h3 > Example</ h3 >
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< pre >
typedef < a href = "../Reference/list.html" > list</ a > < int,char,long,short,char,short,double,long> types;
typedef find< types, short> ::type iter;
BOOST_STATIC_ASSERT((is_same< iter::type,short> ::type::value));
BOOST_STATIC_ASSERT((< a href = "../Reference/distance.html" > distance</ a > < begin< types> ::type,iter > ::type::value == 3));
</ pre >
< p >
< h3 > See also</ h3 >
< p >
< a href = "../Algorithms.html" > Algorithms</ a > , < code >< a href = "../Reference/count_if.html" > count_if</ a ></ code > , < code >< a href = "../Reference/find.html" > find</ a ></ code > , < code >< a href = "../Reference/find_if.html" > find_if</ a ></ code > , < code >< a href = "../Reference/contains.html" > contains</ a ></ code >
< p >< hr >
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< a href = "../Table_of_Contents.html" > Table of Contents</ a >< br > Last edited December 12, 2002 2:05 am</ body ></ html >
