How to Find with Hash Set

c++11 containers intermediate

To find an element in a std::unordered_set we use the find() method. The find() method returns an iterator to a key, meaning an iterator to Key. If nothing was found, the end() iterator is returned from the unordered_set.

#include <unordered_set>
#include <string>
#include <iostream>

int main() {
  std::unordered_set<std::string> planets{
    {"Venus"},
    {"Earth"},
    {"Mars"},
  };

  auto it = planets.find("Earth");
  if (it != planets.end()) {
    std::cout << *it << "\n";
  } else {
    std::cout << "No such planet.\n";
  }
  
  it = planets.find("PlanetX");
  if (it != planets.end()) {
    std::cout << *it << "\n";
  } else {
    std::cout << "No such planet.\n";
  }
}

Earth
No such planet.