JSON for Modern C++  2.0.3
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 = std::int64_t, class NumberUnsignedType = std::uint64_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 ( )
inlinenoexcept

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

Warning
The pointer becomes invalid if the underlying JSON object changes.
Template Parameters
PointerTypepointer type; must be a pointer to array_t, object_t, string_t, boolean_t, number_integer_t, number_unsigned_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.
1 #include <json.hpp>
2 
3 using json = nlohmann::json;
4 
5 int main()
6 {
7  // create a JSON number
8  json value = 17;
9 
10  // explicitly getting pointers
11  auto p1 = value.get<const json::number_integer_t*>();
12  auto p2 = value.get<json::number_integer_t*>();
13  auto p3 = value.get<json::number_integer_t* const>();
14  auto p4 = value.get<const json::number_integer_t* const>();
15  auto p5 = value.get<json::number_float_t*>();
16 
17  // print the pointees
18  std::cout << *p1 << ' ' << *p2 << ' ' << *p3 << ' ' << *p4 << '\n';
19  std::cout << std::boolalpha << (p5 == nullptr) << '\n';
20 }
basic_json<> json
default JSON class
Definition: json.hpp:10122
NumberIntegerType number_integer_t
a type for a number (integer)
Definition: json.hpp:582
NumberFloatType number_float_t
a type for a number (floating-point)
Definition: json.hpp:721
ValueType value(const typename object_t::key_type &key, ValueType default_value) const
access specified object element with default value
Definition: json.hpp:3695
Output (play with this example online):
17 17 17 17
true
The example code above can be translated with
g++ -std=c++11 -Isrc doc/examples/get__PointerType.cpp -o get__PointerType 
See also
get_ptr() for explicit pointer-member access
Since
version 1.0.0

Definition at line 2931 of file json.hpp.