allocator_type array array_t at at at at back back basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json basic_json begin begin boolean_t cbegin cend clear const_pointer const_reference const_reverse_iterator count crbegin crend difference_type dump empty end end erase erase erase erase find find front front get get get get_allocator get_ptr get_ptr insert insert insert insert insert is_array is_boolean is_discarded is_null is_number is_number_float is_number_integer is_object is_primitive is_string is_structured max_size number_float_t number_integer_t object object_t operator value_t operator ValueType operator!= operator!= operator!= operator+= operator+= operator+= operator< operator< operator<< operator<< operator<= operator= operator== operator== operator== operator> operator>= operator>> operator>> operator[] operator[] operator[] operator[] parse parse parse parse_event_t parser_callback_t pointer push_back push_back push_back rbegin rbegin reference rend rend reverse_iterator size size_type string_t swap swap swap swap type value value value_t value_type ~basic_json

template<template< typename U, typename V, typename...Args > class ObjectType = std::map, template< typename U, typename...Args > class ArrayType = std::vector, class StringType = std::string, class BooleanType = bool, class NumberIntegerType = int64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator> template<typename T , std::size_t n> reference nlohmann::basic_json::operator[] ( const T(&)  key[n] ) inline Returns a reference to the element at with specified key key. Note If key is not found in the object, then it is silently added to the object and filled with a null value to make key a valid reference. In case the value was null before, it is converted to an object. This function is required for compatibility reasons with Clang. Parameters [in] key key of the element to access Returns reference to the element at key key Exceptions std::domain_error if JSON is not an object or null Complexity Logarithmic in the size of the container. Example The example below shows how object elements can be read and written using the [] operator. #include <json.hpp> using namespace nlohmann; int main() { // create a JSON object json object = { {"one", 1}, {"two", 2}, {"three", 2.9} }; // output element with key "two" std::cout << object["two"] << "\n\n"; // change element with key "three" object["three"] = 3; // output changed array std::cout << std::setw(4) << object << "\n\n"; // mention nonexisting key object["four"]; // write to nonexisting key object["five"]["really"]["nested"] = true; // output changed object std::cout << std::setw(4) << object << '\n'; } Output (play with this example online): 2 { "one": 1, "three": 3, "two": 2 } { "five": { "really": { "nested": true } }, "four": null, "one": 1, "three": 3, "two": 2 } The example code above can be translated with g++ -std=c++11 -Isrc doc/examples/operatorarray__key_type.cpp -o operatorarray__key_type See also at(const typename object_t::key_type&) for access by reference with range checking value() for access by value with a default value Since version 1.0 Definition at line 2830 of file json.hpp.