JSON for Modern C++ 3.7.3

accept
accept
accept
allocator_type
array
array_t
at
at
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back
back
basic_json
basic_json
basic_json
basic_json
basic_json
basic_json
basic_json
basic_json
basic_json
basic_json
begin
begin
binary
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end
end
erase
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operator value_t
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~basic_json
| ## ◆ operator[]() [2/8]
const_reference nlohmann::basic_json::operator[] | ( | const json_pointer & | ptr | ) | const
| inline
  Uses a JSON pointer to retrieve a reference to the respective JSON value. No bound checking is performed. The function does not change the JSON value; no `null` values are created. In particular, the special value `-` yields an exception. Parameters
  [in] | ptr | JSON pointer to the desired element
  Returns const reference to the element pointed to by ptr Complexity Constant. Exceptions
  parse_error.106 | if an array index begins with '0'
  parse_error.109 | if an array index was not a number
  out_of_range.402 | if the array index '-' is used
  out_of_range.404 | if the JSON pointer can not be resolved
  Example The behavior is shown in the example. 1 #include <iostream> 2 #include <nlohmann/json.hpp> 3 4 using json = nlohmann::json; 5 6 int main() 7 { 8 // create a JSON value 9 const json j = 10 { 11 {"number", 1}, {"string", "foo"}, {"array", {1, 2}} 12 }; 13 14 // read-only access 15 16 // output element with JSON pointer "/number" 17 std::cout << j["/number"_json_pointer] << '\n'; 18 // output element with JSON pointer "/string" 19 std::cout << j["/string"_json_pointer] << '\n'; 20 // output element with JSON pointer "/array" 21 std::cout << j["/array"_json_pointer] << '\n'; 22 // output element with JSON pointer "/array/1" 23 std::cout << j["/array/1"_json_pointer] << '\n'; 24 } Output (play with this example online):
      1
      "foo"
      [1,2]
      2
  The example code above can be translated with
      g++ -std=c++11 -Isingle_include doc/examples/operatorjson_pointer_const.cpp -o operatorjson_pointer_const
Since version 2.0.0 Definition at line 23676 of file json.hpp.

nlohmann::json
basic_json<> json
default JSON class
Definition: json.hpp:2774