unordered_map

unordered_map(C++11)

头文件

#include <unordered_map>

声明

empty (1)	explicit unordered_map ( size_type n = /* see below */, const hasher& hf = hasher(), const key_equal& eql = key_equal(), const allocator_type& alloc = allocator_type() ); explicit unordered_map ( const allocator_type& alloc );
range (2)	template <class InputIterator> unordered_map ( InputIterator first, InputIterator last, size_type n = /* see below */, const hasher& hf = hasher(), const key_equal& eql = key_equal(), const allocator_type& alloc = allocator_type() );
copy (3)	unordered_map ( const unordered_map& ump ); unordered_map ( const unordered_map& ump, const allocator_type& alloc );
move (4)	unordered_map ( unordered_map&& ump ); unordered_map ( unordered_map&& ump, const allocator_type& alloc );
initializer list (5)	unordered_map ( initializer_list<value_type> il, size_type n = /* see below */, const hasher& hf = hasher(), const key_equal& eql = key_equal(), const allocator_type& alloc = allocator_type() );

unordered_map<string,int> student = {
        {"Sherlock",1001},
        {"Batman",1002},
};

// constructing unordered_maps
#include <iostream>
#include <string>
#include <unordered_map>

typedef std::unordered_map<std::string,std::string> stringmap;

stringmap merge (stringmap a,stringmap b) {
  stringmap temp(a); temp.insert(b.begin(),b.end()); return temp;
}

int main ()
{
  stringmap first;                              // empty
  stringmap second ( {{"apple","red"},{"lemon","yellow"}} );       // init list
  stringmap third ( {{"orange","orange"},{"strawberry","red"}} );  // init list
  stringmap fourth (second);                    // copy
  stringmap fifth (merge(third,fourth));        // move
  stringmap sixth (fifth.begin(),fifth.end());  // range

  std::cout << "sixth contains:";
  for (auto& x: sixth) std::cout << " " << x.first << ":" << x.second;
  std::cout << std::endl;

  return 0;
}