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std::experimental::ranges::search_n(3) | C++ Standard Libary | std::experimental::ranges::search_n(3) |
NAME¶
std::experimental::ranges::search_n - std::experimental::ranges::search_n
Synopsis¶
Defined in header <experimental/ranges/algorithm>
template< ForwardIterator I, Sentinel<I> S, class T,
class Pred = ranges::equal_to<>, class Proj = ranges::identity >
requires IndirectlyComparable<I, const T*, Pred, Proj> (1)
(ranges TS)
I search_n(I first, S last, ranges::difference_type_t<I> count,
const T& value, Pred pred = Pred{}, Proj proj = Proj{});
template< ForwardRange R, class T, class Pred =
ranges::equal_to<>,
class Proj = ranges::identity >
requires IndirectlyComparable<ranges::iterator_t<R>, const T*, Pred,
Proj> (2) (ranges TS)
ranges::safe_iterator_t<R> search_n(R&& r,
ranges::difference_type_t<ranges::iterator_t<R>> count,
const T& value, Pred pred = Pred{}, Proj proj = Proj{});
1) Searches the range [first, last) for the first sequence of count elements
whose
projected values are each equal to the given value value according to the
predicate
pred.
2) Same as (1), but uses r as the source range, as if using
ranges::begin(r) as
first and ranges::end(r) as last.
Parameters¶
first, last - the range of elements to examine
r - the range of elements to examine
count - the length of the sequence to search for
value - the value to search for
pred - the predicate that compares the projected elements with value
proj - the projection to apply to the elements
Return value¶
Iterator to the beginning of the found sequence in the range
[first, last). If no
such sequence is found, an iterator that compares equal to last is
returned.
Complexity¶
At most last - first applications of the predicate and the projection.
Possible implementation¶
template< ForwardIterator I, Sentinel<I> S, class T,
class Pred = ranges::equal_to<>, class Proj = ranges::identity >
requires IndirectlyComparable<I, const T*, Pred, Proj>
I search_n(I first, S last, ranges::difference_type_t<I> count,
const T& value, Pred pred = Pred{}, Proj proj = Proj{})
{
for(; first != last; ++first) {
if (!ranges::invoke(pred, ranges::invoke(proj, *first), value)) {
continue;
}
I candidate = first;
ranges::difference_type_t<I> cur_count = 0;
while (true) {
++cur_count;
if (cur_count == count) {
// success
return candidate;
}
++first;
if (first == last) {
// exhausted the list
return first;
}
if (!ranges::invoke(pred, ranges::invoke(proj, *first), value)) {
// too few in a row
break;
}
}
}
return first;
}
Example¶
This section is incomplete
Reason: no example
See also¶
search_n searches a range for a number of consecutive copies of
an element
(function template)
find_end finds the last sequence of elements in a certain range
(function template)
find finds the first element satisfying specific criteria
find_if (function template)
find_if_not
search searches for a range of elements
(function template)
2022.07.31 | http://cppreference.com |