std::ranges::ends_with
Defined in header <algorithm> |
||
---|---|---|
Call signature | ||
template< std::input_iterator I1, std::sentinel_for<I1> S1, std::input_iterator I2, std::sentinel_for<I2> S2, class Pred = ranges::equal_to, class Proj1 = std::identity, class Proj2 = std::identity > requires (std::forward_iterator<I1> || std::sized_sentinel_for<S1, I1>) && (std::forward_iterator<I2> || std::sized_sentinel_for<S2, I2>) && std::indirectly_comparable<I1, I2, Pred, Proj1, Proj2> constexpr bool ends_with( I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {} ); |
(1) | (since C++23) |
template< ranges::input_range R1, ranges::input_range R2, class Pred = ranges::equal_to, class Proj1 = std::identity, class Proj2 = std::identity > requires (ranges::forward_range<R1> || ranges::sized_range<R1>) && (ranges::forward_range<R2> || ranges::sized_range<R2>) && std::indirectly_comparable<ranges::iterator_t<R1>, ranges::iterator_t<R2>, Pred, Proj1, Proj2> constexpr bool ends_with( R1&& r1, R2&& r2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {} ); |
(2) | (since C++23) |
Checks whether the second range matches the suffix of the first range.
N1
and
N2
be
ranges::distance(first1, last1)
and
ranges::distance(first2, last2)
respectively. If
N1 < N2
, returns
false
. Otherwise, returns
true
if only if every element in the range
[first2, last2)
is equal to the corresponding element in
[first1 + N1 - N2, last1)
. Comparison is done by applying the binary predicate
pred
to elements in two ranges projected by
proj1
and
proj2
respectively.
r1
and
r2
as the source ranges, as if using
ranges::begin(r1)
as
first1
,
ranges:begin(r2)
as
first2
,
ranges::end(r1)
as
last1
, and
ranges::end(r2)
as
last2
.
The function-like entities described on this page are niebloids, that is:
- Explicit template argument lists may not be specified when calling any of them.
- None of them is visible to argument-dependent lookup.
- When one of them is found by normal unqualified lookup for the name to the left of the function-call operator, it inhibits argument-dependent lookup.
In practice, they may be implemented as function objects, or with special compiler extensions.
Parameters
first1, last1 | - | the range of elements to examine |
r1 | - | the range of elements to examine |
first2, last2 | - | the range of elements to be used as the suffix |
r2 | - | the range of elements to be used as the suffix |
pred | - | the binary predicate that compares the projected elements |
proj1 | - | the projection to apply to the elements of the range to examine |
proj2 | - | the projection to apply to the elements of the range to be used as the suffix |
Return value
true
if the second range matches the suffix of the first range, false
otherwise.
Complexity
Generally linear: at most min(N1, N2)
applications of the predicate and both projections. The predicate and both projections are not applied if N1 < N2
.
If both N1
and N2
can be calculated in constant time (i.e. both iterator-sentinel type pairs model sized_sentinel_for
, or both range types model sized_range
) and N1 < N2
, the time complexity is constant.
Possible implementation
struct ends_with_fn { template<std::input_iterator I1, std::sentinel_for<I1> S1, std::input_iterator I2, std::sentinel_for<I2> S2, class Pred = ranges::equal_to, class Proj1 = std::identity, class Proj2 = std::identity> requires (std::forward_iterator<I1> || std::sized_sentinel_for<S1, I1>) && (std::forward_iterator<I2> || std::sized_sentinel_for<S2, I2>) && std::indirectly_comparable<I1, I2, Pred, Proj1, Proj2> constexpr bool operator()(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {}) const { const auto n1 = ranges::distance(first1, last1); const auto n2 = ranges::distance(first2, last2); if (n1 < n2) return false; ranges::advance(first1, n1 - n2); return ranges::equal(std::move(first1), std::move(last1), std::move(first2), std::move(last2), std::move(pred), std::move(proj1), std::move(proj2)); } template<ranges::input_range R1, ranges::input_range R2, class Pred = ranges::equal_to, class Proj1 = std::identity, class Proj2 = std::identity> requires (ranges::forward_range<R1> || ranges::sized_range<R1>) && (ranges::forward_range<R2> || ranges::sized_range<R2>) && std::indirectly_comparable<ranges::iterator_t<R1>, ranges::iterator_t<R2>, Pred, Proj1, Proj2> constexpr bool operator()(R1&& r1, R2&& r2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {}) const { return (*this)(ranges::begin(r1), ranges::end(r1), ranges::begin(r2), ranges::end(r2), std::move(pred), std::move(proj1), std::move(proj2)); } }; inline constexpr ends_with_fn ends_with{}; |
Notes
Feature testing macro: __cpp_lib_ranges_starts_ends_with
.
Example
#include <algorithm> #include <array> #include <iostream> int main() { std::cout << std::boolalpha << std::ranges::ends_with("static_cast", "cast") << '\n' << std::ranges::ends_with("const_cast", "cast") << '\n' << std::ranges::ends_with("reinterpret_cast", "cast") << '\n' << std::ranges::ends_with("dynamic_cast", "cast") << '\n' << std::ranges::ends_with("move", "cast") << '\n' << std::ranges::ends_with("move_if_noexcept", "cast") << '\n' << std::ranges::ends_with("forward", "cast") << '\n'; static_assert( ! std::ranges::ends_with("as_const", "cast") and !! std::ranges::ends_with("bit_cast", "cast") and ! std::ranges::ends_with("to_underlying", "cast") and !! std::ranges::ends_with(std::array{1,2,3,4}, std::array{3,4}) and ! std::ranges::ends_with(std::array{1,2,3,4}, std::array{4,5}) ); }
Output:
true true true true false false false
See also
(C++23)
|
checks whether a range starts with another range (niebloid) |
(C++20)
|
checks if the string ends with the given suffix (public member function of std::basic_string<CharT,Traits,Allocator> ) |
(C++20)
|
checks if the string view ends with the given suffix (public member function of std::basic_string_view<CharT,Traits> ) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/algorithm/ranges/ends_with