std::search_n

 

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Algorithm library

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Non-modifying sequence operations
all_of any_of none_of (C++11) (C++11) (C++11) for_each count count_if mismatch equal	find find_if find_if_not (C++11) find_end find_first_of adjacent_find search search_n
Modifying sequence operations
copy copy_if (C++11) copy_n (C++11) copy_backward move (C++11) move_backward (C++11) fill fill_n transform generate generate_n remove remove_if remove_copy remove_copy_if	replace replace_if replace_copy replace_copy_if swap swap_ranges iter_swap reverse reverse_copy rotate rotate_copy random_shuffle shuffle   (C++11) unique unique_copy
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is_partitioned (C++11) partition partition_copy (C++11)	stable_partition partition_point (C++11)
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is_sorted (C++11) is_sorted_until (C++11) sort	partial_sort partial_sort_copy stable_sort nth_element
Binary search operations (on sorted ranges)
lower_bound upper_bound	binary_search equal_range
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merge inplace_merge includes	set_difference set_intersection set_symmetric_difference set_union
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is_heap is_heap_until (C++11) make_heap	push_heap pop_heap sort_heap
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max max_element min min_element minmax (C++11) minmax_element (C++11)	lexicographical_compare is_permutation (C++11) next_permutation prev_permutation
Numeric operations
iota (C++11) accumulate inner_product	adjacent_difference partial_sum
C library
qsort	bsearch

 

Defined in header <algorithm>
template< class ForwardIt, class Size, class T > ForwardIt1 search_n( ForwardIt first, ForwardIt last, Size count, const T& value );	(1)
template< class ForwardIt, class Size, class T, class BinaryPredicate > ForwardIt1 search_n( ForwardIt first, ForwardIt last, Size count, const T& value,                      BinaryPredicate p );	(2)

Searches the range [first, last) for the first sequence of count identical elements, each equal to the given value value. The first version uses operator== to compare the elements, the second version uses the given binary predicate p.

Parameters

first, last	-	the range of elements to examine
count	-	the length of the sequence to search for
value	-	the value of the elements to search for
p	-	binary predicate which returns ​true if the elements should be treated as equal. The signature of the predicate function should be equivalent to the following: bool pred(const Type1 &a, const Type2 &b); The signature does not need to have const &, but the function must not modify the objects passed to it. The type  Type1 must be such that an object of type ForwardIt can be dereferenced and then implicitly converted to  Type1. The type  Type2 must be such that an object of type T can be implicitly converted to  Type2. ​
Type requirements
- ForwardIt must meet the requirements of ForwardIterator.

Return value

Iiterator to the beginning of the found sequence in the range [first, last). If no such sequence is found, last is returned.

Complexity

At most last - first applications of the predicate.

Possible implementation

First version
template<class ForwardIt, class Size, class T> ForwardIt1 search_n(ForwardIt first, ForwardIt last, Size count, const T& value) { Size curr_count = 0; ForwardIt result, t_last = first; std::advance(t_last, std::distance(first, last) - count + 1);   for (; first != t_last; first++) { curr_count = 0; result = first; while (*first == value) { curr_count++; if (curr_count == count) { return result; } ++first; } } return last; }
Second version
template<class ForwardIt, class Size, class T, class BinaryPredicate> ForwardIt1 search_n(ForwardIt first, ForwardIt last, Size count, const T& value, BinaryPredicate p) { Size curr_count = 0; ForwardIt result, t_last = first; std::advance(t_last, std::distance(first, last) - count + 1);   for (; first != t_last; first++) { curr_count = 0; result = first; while (p(*first == value)) { curr_count++; if (curr_count == count) { return result; } ++first; } } return last; }

See also

find_end	finds the last sequence of elements in a certain range (function template)
find find_if find_if_not (C++11)	finds the first element satisfying specific criteria (function template)
search	searches for a range of elements (function template)