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调用签名
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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 = {});
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(1) |
(C++23 起) |
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 = {});
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(2) |
(C++23 起) |
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检查第二范围是否匹配第一范围的后缀。
1) 令 N1 与 N2 分别为 ranges::distance(first1, last1) 与 ranges::distance(first2, last2) 。若 N1 < N2 则返回 false 。否则，当且仅当
[first2, last2) 范围中的每个元素均等于 [first1 + N1 - N2, last1) 中的对应元素才返回 true 。通过应用二元谓词
pred 到分别由 proj1 与 proj2 投影的两个范围中的元素进行比较。
2) 同， (1) ，但以 r1 与
r2 为源范围，如同以 ranges::begin(r1) 为 first1 ，以 ranges:begin(r2) 为 first2 ，以 ranges::end(r1) 为 last1 ，并以 ranges::end(r2) 为
last2 。
此页面上描述的仿函数实体是 niebloid，即：
实际上，它们能以函数对象，或者某些特殊编译器扩展实现。
参数
| first1, last1
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-
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要检验的元素范围
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| r1
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-
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要检验的元素范围
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| first2, last2
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要用作后缀的元素范围
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| r2
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-
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要用作后缀的元素范围
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| pred
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-
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比较投影后元素的二元谓词
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| proj1
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-
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应用到要检验的元素范围的投影
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| proj2
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-
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应用到要用作后缀的元素范围的投影
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返回值
若第二范围匹配第一范围的后缀则为 true ，否则为 false 。
复杂度
线性：至多应用 min(N1, N2) 次谓词和两个投影。若 N1
< N2 则不应用谓词和两个投影。
若 N1 与 N2 均能以常数时间计算（即两个迭代器-哨位类型对均实现 sized_sentinel_for ，或两个范围类型均实现 sized_range ）且 N1 < N2
，则时间复杂度为常数。
可能的实现
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{};
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示例
#include <array>
#include <algorithm>
#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'
<< std::ranges::ends_with("as_const", "cast") << '\n'
<< std::ranges::ends_with("bit_cast", "cast") << '\n'
<< std::ranges::ends_with("to_underlying", "cast") << '\n';
<< std::ranges::ends_with(std::array{1,2,3,4}, std::array{3,4}) << '\n'
<< std::ranges::ends_with(std::array{1,2,3,4}, std::array{4,5}) << '\n';
}
输出：
true
true
true
true
false
false
false
false
true
false
参阅
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检查一个范围是否始于另一范围
(niebloid) |
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检查字符串是否终于给定后缀
(std::basic_string<CharT,Traits,Allocator>
的公开成员函数) |
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检查 string_view 是否终于给定后缀
(std::basic_string_view<CharT,Traits> 的公开成员函数) |