JSON for Modern C++ 3.0

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~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>
reference nlohmann::basic_json::at | ( | const typename object_t::key_type & | key | ) |
| inline
  Returns a reference to the element at with specified key key, with bounds checking. 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
  std::out_of_range | if the key key is is not stored in the object; that is, `find(key) == end()`
  Complexity Logarithmic in the size of the container. Example The example below shows how object elements can be read and written using at. 1 #include <json.hpp> 2 3 using namespace nlohmann; 4 5 int main() 6 { 7 // create JSON object 8 json object = 9 { 10 {"the good", "il buono"}, 11 {"the bad", "il cativo"}, 12 {"the ugly", "il brutto"} 13 }; 14 15 // output element with key "the ugly" 16 std::cout << object.at("the ugly") << '\n'; 17 18 // change element with key "the bad" 19 object.at("the bad") = "il cattivo"; 20 21 // output changed array 22 std::cout << object << '\n'; 23 24 // try to write at a nonexisting key 25 try 26 { 27 object.at("the fast") = "il rapido"; 28 } 29 catch (std::out_of_range) 30 { 31 std::cout << "out of range" << '\n'; 32 } 33 } nlohmann::basic_json a class to store JSON values Definition: json.hpp:130 nlohmann::basic_json::at reference at(size_type idx) access specified array element with bounds checking Definition: json.hpp:2412 nlohmann namespace for Niels Lohmann Definition: json.hpp:55 Output (play with this example online):
      "il brutto"
      {"the bad":"il cattivo","the good":"il buono","the ugly":"il brutto"}
      out of range
  The example code above can be translated with
      g++ -std=c++11 -Isrc doc/examples/at__object_t_key_type.cpp -o at__object_t_key_type