std::search

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Defined in header <algorithm>
template< class ForwardIterator1, class ForwardIterator2 > ForwardIterator1 search( ForwardIterator1 first, ForwardIterator1 last,                          ForwardIterator2 s_first, ForwardIterator2 s_last );	(1)
template< class ForwardIterator1, class ForwardIterator2, class BinaryPredicate > ForwardIterator1 search( ForwardIterator1 first, ForwardIterator1 last,                          ForwardIterator2 s_first, ForwardIterator2 s_last, BinaryPredicate p );	(2)

Searches for the first subsequence of elements [s_first, s_last) in the range [first, last). 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
s_first, s_last	-	the range of 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 types  Type1 and  Type2 must be such that objects of types ForwardIterator1 and ForwardIterator2 can be dereferenced and then implicitly converted to  Type1 and  Type2 respectively. ​

Return value

iterator to the beginning of first subsequence [s_first, s_last) in the range [first, last). If no such subsequence is found, last is returned.

Complexity

At most S*N comparisons where S = std::distance(s_first, s_last) and N = std::distance(first, last).

Possible implementation

First version
template<class ForwardIterator1, class ForwardIterator2> ForwardIterator1 search(ForwardIterator1 first, ForwardIterator1 last, ForwardIterator2 s_first, ForwardIterator2 s_last) { ForwardIterator1 t_last = first; size_t cmp_len = std::distance(first, last) - std::distance(s_first - s_last) + 1; std::advance(t_last, cmp_len);   for (; first != t_last; ++first) { ForwardIterator1 it = first; ForwardIterator2 s_it = s_first; while (*it == *s_it) { ++it; ++s_it; if (s_it == s_last) { return first; } } } return last; }
Second version
template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate> ForwardIterator1 search(ForwardIterator1 first, ForwardIterator1 last, ForwardIterator2 s_first, ForwardIterator2 s_last, BinaryPredicate p) { ForwardIterator1 t_last = first;   size_t cmp_len = std::distance(first, last) - std::distance(s_first - s_last) + 1; std::advance(t_last, cmp_len);   for (; first != t_last; ++first) { ForwardIterator1 it = first; ForwardIterator2 s_it = s_first; while (p(*it, *s_it)) { ++it; ++s_it; if (s_it == s_last) { return first; } } } return last; }

See also

find_end	finds the last sequence of elements in a certain range (function template)
equal	determines if two sets of elements are the same (function template)
find find_if find_if_not (C++11)	finds the first element satisfying specific criteria (function template)
lexicographical_compare	returns true if one range is lexicographically less than another (function template)
mismatch	finds the first position where two ranges differ (function template)
search_n	searches for a number consecutive copies of an element in a range (function template)