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| Sequence | ||||
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| Associative | ||||
| Unordered associative | ||||
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| Iterator invalidation | ||||
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| Non-member function table |
std::map| Member functions | |||||||
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| Deduction guides(C++17) | |||||||
template<class C2> void merge(std::map<Key, T, C2, Allocator>& source); | (1) | (since C++17) (constexpr since C++26) |
template<class C2> void merge(std::map<Key, T, C2, Allocator>&& source); | (2) | (since C++17) (constexpr since C++26) |
template<class C2> void merge(std::multimap<Key, T, C2, Allocator>& source); | (3) | (since C++17) (constexpr since C++26) |
template<class C2> void merge(std::multimap<Key, T, C2, Allocator>&& source); | (4) | (since C++17) (constexpr since C++26) |
Attempts to extract (“splice”) each element insource and insert it into*this using the comparison object of*this.If there is an element in*this with key equivalent to the key of an element fromsource, then that element is not extracted fromsource.Ifget_allocator()== source.get_allocator() isfalse, the behavior is undefined.
No elements are copied or moved, only the internal pointers of the container nodes are repointed. All pointers and references to the transferred elements remain valid, but now refer into*this, not intosource.
Contents |
| source | - | compatible container to transfer the nodes from |
Does not throw unless comparison throws.
Given\(\scriptsize S\)S assize() and\(\scriptsize N\)N assource.size():
#include <iostream>#include <map>#include <string> int main(){std::map<int,std::string> ma{{1,"apple"},{5,"pear"},{10,"banana"}};std::map<int,std::string> mb{{2,"zorro"},{4,"batman"},{5,"X"},{8,"alpaca"}};std::map<int,std::string> u; u.merge(ma);std::cout<<"ma.size(): "<< ma.size()<<'\n'; u.merge(mb);std::cout<<"mb.size(): "<< mb.size()<<'\n';std::cout<<"mb.at(5): "<< mb.at(5)<<'\n';for(constauto& kv: u)std::cout<< kv.first<<", "<< kv.second<<'\n';}
Output:
ma.size(): 0mb.size(): 1mb.at(5): X1, apple2, zorro4, batman5, pear8, alpaca10, banana
(C++17) | extracts nodes from the container (public member function)[edit] |
| inserts elementsor nodes(since C++17) (public member function)[edit] |
