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| Sequence | ||||
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| Associative | ||||
| Unordered associative | ||||
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| Iterator invalidation | ||||
| Member function table | ||||
| Non-member function table |
std::unordered_multimap| Member types | ||||||
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| Deduction guides(C++17) | ||||||
void swap( unordered_multimap& other); | (since C++11) (until C++17) | |
void swap( unordered_multimap& other)noexcept(/* see below */); | (since C++17) (constexpr since C++26) | |
Exchanges the contents of the container with those ofother. Does not invoke any move, copy, or swap operations on individual elements.
All iterators and references remain valid. Theend() iterator is invalidated.Hash andKeyEqual must beSwappable, and objects of these types are exchanged using unqualified calls to non-memberswap.Ifstd::allocator_traits<allocator_type>::propagate_on_container_swap::value istrue, then the allocators are exchanged using an unqualified call to non-memberswap. Otherwise, they are not swapped (and ifget_allocator()!= other.get_allocator(), the behavior is undefined).
Contents |
| other | - | container to exchange the contents with |
Any exception thrown by the swap of the | (until C++17) |
noexcept specification: noexcept(std::allocator_traits<Allocator>::is_always_equal::value &&std::is_nothrow_swappable<Hash>::value | (since C++17) |
Constant.
#include <iostream>#include <string>#include <utility>#include <unordered_map> // print out a std::pairtemplate<class Os,class U,class V>Os& operator<<(Os& os,conststd::pair<U, V>& p){return os<< p.first<<':'<< p.second;} // print out a containertemplate<class Os,class Co>Os& operator<<(Os& os,const Co& co){ os<<'{';for(constauto& i: co) os<<' '<< i;return os<<" }\n";} int main(){std::unordered_multimap<std::string,std::string> m1{{"γ","gamma"},{"β","beta"},{"α","alpha"},{"γ","gamma"}}, m2{{"ε","epsilon"},{"δ","delta"},{"ε","epsilon"}}; constauto& ref=*(m1.begin());constauto iter=std::next(m1.cbegin()); std::cout<<"──────── before swap ────────\n"<<"m1: "<< m1<<"m2: "<< m2<<"ref: "<< ref<<"\niter: "<<*iter<<'\n'; m1.swap(m2); std::cout<<"──────── after swap ────────\n"<<"m1: "<< m1<<"m2: "<< m2<<"ref: "<< ref<<"\niter: "<<*iter<<'\n'; // Note that every iterator referring to an element in one container before// the swap refers to the same element in the other container after the swap.// Same is true for references.}
Possible output:
──────── before swap ────────m1: { α:alpha β:beta γ:gamma γ:gamma }m2: { δ:delta ε:epsilon ε:epsilon }ref: α:alphaiter: β:beta──────── after swap ────────m1: { δ:delta ε:epsilon ε:epsilon }m2: { α:alpha β:beta γ:gamma γ:gamma }ref: α:alphaiter: β:beta| specializes thestd::swap algorithm (function template)[edit] |
