std::unordered_map::emplace

Parameters

args

Arguments used to construct a new object of the mapped type for the inserted element.

Arguments forwarded to construct the new element (of type pair<const key_type, mapped_type>).
This can be one of:
- Two arguments: one for the key, the other for the mapped value.
- A single argument of a pair type with a value for the key as first member, and a value for the mapped value as second.
- piecewise_construct as first argument, and two additional arguments with tuples to be forwarded as arguments for the key value and for the mapped value respectivelly.
See pair::pair for more info.

Return value

Example

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// unordered_map::emplace
#include <iostream>
#include <string>
#include <unordered_map>
int main ()
{
  std::unordered_map<std::string,std::string> mymap;
  mymap.emplace ("NCC-1701", "J.T. Kirk");
  mymap.emplace ("NCC-1701-D", "J.L. Picard");
  mymap.emplace ("NCC-74656", "K. Janeway");
  std::cout << "mymap contains:" << std::endl;
  for (auto& x: mymap)
    std::cout << x.first << ": " << x.second << std::endl;
  std::cout << std::endl;
  return 0;
}

mymap contains:
NCC-1701: J.T. Kirk
NCC-1701-D: J.L. Picard
NCC-74656: K. Janeway

Complexity

Iterator validity

See also

unordered_map::insert

Insert elements (public member function)

unordered_map::operator[]

Access element (public member function)

unordered_map::at

Access element (public member function)