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>
const_reference nlohmann::basic_json::at | ( | const typename object_t::key_type & | key | ) | const
| inline
  Returns a const reference to the element at with specified key key, with bounds checking. Parameters
  [in] | key | key of the element to access
  Returns const 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 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 // try to read from a nonexisting key 19 try 20 { 21 std::cout << object.at("the fast") << '\n'; 22 } 23 catch (std::out_of_range) 24 { 25 std::cout << "out of range" << '\n'; 26 } 27 } nlohmann::basic_json a class to store JSON values Definition: json.hpp:121 nlohmann namespace for Niels Lohmann Definition: json.hpp:56 nlohmann::basic_json::at reference at(size_type idx) access specified array element with bounds checking Definition: json.hpp:2064 Output:
      "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_const.cpp -o at__object_t_key_type_const
.