unordered_set

unordered_set<int> m(nums1.begin(), nums1.end());

Construct

` int main ()
{
std::unordered_setstd::string first; // empty
std::unordered_setstd::string second ( {"red","green","blue"} ); // init list
std::unordered_setstd::string third ( {"orange","pink","yellow"} ); // init list
std::unordered_setstd::string fourth ( second ); // copy
std::unordered_setstd::string fifth ( cmerge(third,fourth) ); // move
std::unordered_setstd::string sixth ( fifth.begin(), fifth.end() ); // range

std::cout << "sixth contains:";  
for (const std::string& x: sixth) std::cout << " " << x;  
std::cout << std::endl;  

return 0;  

} `
Possible output:
sixth contains: pink yellow red green orange blue

Capacity

empty,size,max_size
` int main ()
{
std::unordered_setstd::string myset;
std::cout << "0. size: " << myset.size() << std::endl;

myset = {"milk","potatoes","eggs"};  
std::cout << "1. size: " << myset.size() << std::endl;  

myset.insert ("pineapple");  
std::cout << "2. size: " << myset.size() << std::endl;  

myset.erase ("milk");  
std::cout << "3. size: " << myset.size() << std::endl;  

return 0;  

} `

Output:
0. size: 0

1. size: 3
2. size: 4
3. size: 3

Iterators

begin, end, cbegin, cend

Element lookup

find, count, equal_range

Modifiers

emplace, insert, erase, clear, swap

Hash policy

reverse