front.cpp 951 B

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  1. #include <iostream>
  2. #include <nlohmann/json.hpp>
  3. using json = nlohmann::json;
  4. int main()
  5. {
  6. // create JSON values
  7. json j_null;
  8. json j_boolean = true;
  9. json j_number_integer = 17;
  10. json j_number_float = 23.42;
  11. json j_object = {{"one", 1}, {"two", 2}};
  12. json j_object_empty(json::value_t::object);
  13. json j_array = {1, 2, 4, 8, 16};
  14. json j_array_empty(json::value_t::array);
  15. json j_string = "Hello, world";
  16. // call front()
  17. //std::cout << j_null.front() << '\n'; // would throw
  18. std::cout << j_boolean.front() << '\n';
  19. std::cout << j_number_integer.front() << '\n';
  20. std::cout << j_number_float.front() << '\n';
  21. std::cout << j_object.front() << '\n';
  22. //std::cout << j_object_empty.front() << '\n'; // undefined behavior
  23. std::cout << j_array.front() << '\n';
  24. //std::cout << j_array_empty.front() << '\n'; // undefined behavior
  25. std::cout << j_string.front() << '\n';
  26. }