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
count
crbegin
crend
difference_type
dump
empty
end
end
erase
erase
erase
erase
find
find
front
front
get
get
get_allocator
get_ptr
is_array
is_boolean
is_discarded
is_null
is_number
is_number_float
is_number_integer
is_object
is_primitive
is_string
is_structured
list_init_t
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[]
parse
parse
parse_event_t
parser_callback_t
pointer
push_back
push_back
push_back
rbegin
rbegin
reference
rend
rend
size
size_type
string_t
swap
swap
swap
swap
type
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 PointerType , typename std::enable_if< std::is_pointer< PointerType >::value, int >::type = 0>

PointerType nlohmann::basic_json::get_ptr | ( |  | ) | const

inlinenoexcept

Implict pointer access to the internally stored JSON value. No copies are made.

Warning
  Writing data to the pointee of the result yields an undefined state.

Template Parameters

  PointerType | pointer type; must be a pointer to array_t, object_t, string_t, boolean_t, number_integer_t, or number_float_t.

Returns
  pointer to the internally stored JSON value if the requested pointer type PointerType fits to the JSON value; `nullptr` otherwise

Complexity
  Constant.

Example
  The example below shows how pointers to internal values of a JSON value can be requested. Note that no type conversions are made and a `nullptr` is returned if the value and the requested pointer type does not match.
  #include <json.hpp>
  using namespace nlohmann;
  int main()
  {
  // create a JSON boolean
  json value = 17;
  // explicitly getting pointers
  auto p1 = value.get_ptr<const json::number_integer_t*>();
  auto p2 = value.get_ptr<json::number_integer_t*>();
  auto p3 = value.get_ptr<json::number_integer_t* const>();
  auto p4 = value.get_ptr<const json::number_integer_t* const>();
  auto p5 = value.get_ptr<json::number_float_t*>();
  // print the pointees
  std::cout << *p1 << ' ' << *p2 << ' ' << *p3 << ' ' << *p4 << '\n';
  std::cout << std::boolalpha << (p5 == nullptr) << '\n';
  }
  nlohmann::basic_json::get_ptr
  PointerType get_ptr() const noexcept
  get a pointer value (implicit)
  Definition: json.hpp:2005
  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::number_integer_t
  NumberIntegerType number_integer_t
  a type for a number (integer)
  Definition: json.hpp:197
  nlohmann::basic_json::number_float_t
  NumberFloatType number_float_t
  a type for a number (floating-point)
  Definition: json.hpp:199
  Output:

      17 17 17 17
      true

  The example code above can be translated with

      g++ -std=c++11 -Isrc doc/examples/get_ptr.cpp -o get_ptr

  .