| 1234567891011121314151617181920212223242526272829303132333435363738 | #include <iostream>#include <nlohmann/json.hpp>using json = nlohmann::json;int main(){    // create JSON values    json j_boolean = true;    json j_number_integer = 17;    json j_number_float = 23.42;    json j_object = {{"one", 1}, {"two", 2}};    json j_object_empty(json::value_t::object);    json j_array = {1, 2, 4, 8, 16};    json j_array_empty(json::value_t::array);    json j_string = "Hello, world";    // call back()    std::cout << j_boolean.back() << '\n';    std::cout << j_number_integer.back() << '\n';    std::cout << j_number_float.back() << '\n';    std::cout << j_object.back() << '\n';    //std::cout << j_object_empty.back() << '\n';  // undefined behavior    std::cout << j_array.back() << '\n';    //std::cout << j_array_empty.back() << '\n';   // undefined behavior    std::cout << j_string.back() << '\n';    // back() called on a null value    try    {        json j_null;        j_null.back();    }    catch (json::invalid_iterator& e)    {        std::cout << e.what() << '\n';    }}
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