std::hash<std::vector<bool>>

 

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std::vector<bool>

Member types
vector<bool>::reference
Member functions
vector::vector vector::~vector vector::operator= vector::assign vector::assign_range (C++23) vector::get_allocator Element access vector::operator[] vector::at vector::front vector::back Iterators vector::beginvector::cbegin (C++11) vector::endvector::cend (C++11) vector::rbeginvector::crbegin (C++11) vector::rendvector::crend (C++11)	Capacity vector::empty vector::size vector::max_size vector::capacity vector::resize vector::reserve vector::shrink_to_fit (DR*) Modifiers vector::clear vector::erase vector::insert vector::insert_range (C++23) vector::append_range (C++23) vector::emplace (C++11) vector::emplace_back (C++11) vector::push_back vector::pop_back vector::swap vector<bool>::flip vector<bool>::swap
Non-member functions
operator==operator<=> (C++20) swap(std::vector<bool>) erase(std::vector<bool>)erase_if(std::vector<bool>) (C++20)(C++20)	operator!=operator<operator>operator<=operator>= (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)
Helper classes
hash<std::vector<bool>> (C++11)
Deduction guides(C++17)

 

Defined in header <vector>
template<class Allocator > struct hash<std::vector<bool, Allocator>>;		(since C++11)

The template specialization of std::hash for std::vector<bool> allows users to obtain hashes of objects of type std::vector<bool>.

Example

Run this code

#include <iostream>#include <unordered_set>#include <vector>   using vb =std::vector<bool>;   vb to_vector_bool(unsigned n){ vb v;do{ v.push_back(n &1); n >>=1;}while(n);return v;}   auto print(const vb& v, bool new_line =true){for(std::cout<<"{ ";constbool e : v)std::cout<< e <<' ';std::cout<<'}'<<(new_line ?'\n':' ');}   int main(){for(auto i{0U}; i !=8;++i){std::cout<<std::hex<<std::uppercase; vb v = to_vector_bool(i);std::cout<<std::hash<vb>{}(v)<<' '<<std::dec; print(v);}   // std::hash for vector<bool> makes it possible to keep them in// unordered_* associative containers, such as unordered_set.   std::unordered_set v{vb{0}, vb{0, 0}, vb{1}, vb{1}, vb{1, 0}, vb{1, 1}};   for(vb const& e : v) print(e, 0);std::cout<<'\n';}

Possible output:

6D09EE26D5863619 { 0 } 3C27D9F591D20E49 { 1 } E74D3F72B7599C63 { 0 1 } EE3BE81F55123770 { 1 1 } 3AAD2A2EDBEC6C35 { 0 0 1 } EB057F773CB64C43 { 1 0 1 } 6E1354730102BE00 { 0 1 1 } E2E622597C18899D { 1 1 1 } { 1 1 } { 1 0 } { 1 } { 0 0 } { 0 }

See also

hash (C++11)

hash function object (class template)