Returns the first mismatching pair of projected elements from two ranges: one defined by[first1, last1) orr1 and another defined by[first2, last2) orr2.

The function-like entities described on this page arealgorithm function objects (informally known asniebloids), that is:

• Explicit template argument lists cannot be specified when calling any of them.
• None of them are visible toargument-dependent lookup.
• When any of them are found bynormal unqualified lookup as the name to the left of the function-call operator,argument-dependent lookup is inhibited.

[edit]Parameters

[edit]Return value

ranges::mismatch_result with iterators to the first two non-equal elements.

If no mismatches are found when the comparison reacheslast1 orlast2, whichever happens first, the object holds the end iterator and the corresponding iterator from the other range.

[edit]Complexity

At moststd::min(last1- first1, last2- first2) applications of the predicate and corresponding projections.

[edit]Possible implementation

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>    requiresstd::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(notstd::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>    requiresstd::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));}}; inlineconstexpr mismatch_fn mismatch;

[edit]Example

#include <algorithm>#include <iostream>#include <ranges>#include <string_view> [[nodiscard]]constexprstd::string_view mirror_ends(conststd::string_view in){constauto 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'; usingnamespace std::literals::string_view_literals;     static_assert("123"sv== mirror_ends("123!@#321"));    static_assert("radar"sv== mirror_ends("radar"));}

abaABBAlevel

[edit]See also

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