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::indirectly_comparable<I1, I2, Pred, Proj1, Proj2> constexpr mismatch_result<I1, I2> mismatch( I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {} ); | (1) | (since C++20) |
template< ranges::input_range R1, ranges::input_range R2, class Pred = ranges::equal_to, class Proj1 = std::identity, class Proj2 = std::identity > requires std::indirectly_comparable< ranges::iterator_t<R1>, ranges::iterator_t<R2>, Pred, Proj1, Proj2> constexpr mismatch_result<ranges::borrowed_iterator_t<R1>, ranges::borrowed_iterator_t<R2>> mismatch( R1&& r1, R2&& r2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {} ); | (2) | (since C++20) |
Helper types | ||
template< class I1, class I2 > using mismatch_result = ranges::in_in_result<I1, I2>; | (3) | (since C++20) |
Returns the first mismatching pair of projected elements from two ranges: one defined by [
first1
,
last1
)
or r1
and another defined by [
first2
,
last2
)
or r2
.
p
.r
as the source range, as if using ranges::begin(r)
as first
and ranges::end(r)
as last
.The function-like entities described on this page are niebloids, that is:
In practice, they may be implemented as function objects, or with special compiler extensions.
first1, last1 | - | an iterator-sentinel pair denoting the first range of the elements to compare |
r1 | - | the first range of the elements to compare |
first2, last2 | - | an iterator-sentinel pair denoting the second range of the elements to compare |
r2 | - | the second range of the elements to compare |
pred | - | predicate to apply to the projected elements |
proj1 | - | projection to apply to the first range of elements |
proj2 | - | projection to apply to the second range of elements |
ranges::mismatch_result
with iterators to the first two non-equal elements.
If no mismatches are found when the comparison reaches last1
or last2
, whichever happens first, the object holds the end iterator and the corresponding iterator from the other range.
At most std::min(last1 - first1, last2 - first2)
applications of the predicate and corresponding projections.
struct mismatch_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::indirectly_comparable<I1, I2, Pred, Proj1, Proj2> constexpr std::mismatch_result<I1, I2> operator()(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {}) const { for (; first1 != last1 && first2 != last2; ++first1, (void)++first2) if (not std::invoke(pred, std::invoke(proj1, *first1), std::invoke(proj2, *first2))) break; return {first1, first2}; } template<ranges::input_range R1, ranges::input_range R2, class Pred = ranges::equal_to, class Proj1 = std::identity, class Proj2 = std::identity> requires std::indirectly_comparable<ranges::iterator_t<R1>, ranges::iterator_t<R2>, Pred, Proj1, Proj2> constexpr ranges::mismatch_result<ranges::borrowed_iterator_t<R1>, ranges::borrowed_iterator_t<R2>> 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::ref(pred), std::ref(proj1), std::ref(proj2)); } }; inline constexpr mismatch_fn mismatch; |
This program determines the longest substring that is simultaneously found at the very beginning and at the very end of the given string, in reverse order (possibly overlapping).
#include <algorithm> #include <iostream> #include <ranges> #include <string_view> [[nodiscard]] constexpr std::string_view mirror_ends(const std::string_view in) { const auto end = std::ranges::mismatch(in, in | std::views::reverse).in1; return {in.cbegin(), end}; } int main() { std::cout << mirror_ends("abXYZba") << '\n' << mirror_ends("abca") << '\n' << mirror_ends("ABBA") << '\n' << mirror_ends("level") << '\n'; using namespace std::literals::string_view_literals; static_assert("123"sv == mirror_ends("123!@#321")); static_assert("radar"sv == mirror_ends("radar")); }
Output:
ab a ABBA level
(C++20) | determines if two sets of elements are the same (niebloid) |
(C++20)(C++20)(C++20) | finds the first element satisfying specific criteria (niebloid) |
(C++20) | returns true if one range is lexicographically less than another (niebloid) |
(C++20) | searches for a range of elements (niebloid) |
finds the first position where two ranges differ (function template) |
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