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Front Page / Algorithms / Querying Algorithms / find_if |
template< typename Sequence , typename Pred > struct find_if { typedef unspecified type; };
Returns an iterator to the first element in Sequence that satisfies the predicate Pred.
#include <boost/mpl/find_if.hpp>
Parameter | Requirement | Description |
---|---|---|
Sequence | Forward Sequence | A sequence to search in. |
Pred | Unary Lambda Expression | A search condition. |
For any Forward Sequence s and unary Lambda Expression pred:
typedef find_if<s,pred>::type i;
Return type: | Forward Iterator. |
---|---|
Semantics: | i is the first iterator in the range [begin<s>::type, end<s>::type) such that apply< pred,deref<i>::type >::type::value == true If no such iterator exists, i is identical to end<s>::type. |
Linear. At most size<s>::value applications of pred.
typedef vector<char,int,unsigned,long,unsigned long> types; typedef find_if<types, is_same<_1,unsigned> >::type iter; BOOST_MPL_ASSERT(( is_same< deref<iter>::type, unsigned > )); BOOST_MPL_ASSERT_RELATION( iter::pos::value, ==, 2 );