JSON for Modern C++ 2.1.1
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◆ get() [5/5]

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 T, typename SFINAE=void > class JSONSerializer = adl_serializer>
template<typename PointerType , typename std::enable_if< std::is_pointer< PointerType >::value, int >::type = 0>
PointerType nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer >::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\n Constant.
Example\n 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
3using json = nlohmann::json;
4
5int 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*>();
13 auto p3 = value.get<json::number_integer_t* const>();
14 auto p4 = value.get<const json::number_integer_t* const>();
16
17 // print the pointees
18 std::cout << *p1 << ' ' << *p2 << ' ' << *p3 << ' ' << *p4 << '\n';
19 std::cout << std::boolalpha << (p5 == nullptr) << '\n';
20}
static basic_json array(std::initializer_list< basic_json > init=std::initializer_list< basic_json >())
explicitly create an array from an initializer list
Definition json.hpp:2165
basic_json get() const
get special-case overload
Definition json.hpp:3173
NumberFloatType number_float_t
a type for a number (floating-point)
Definition json.hpp:1618
NumberIntegerType number_integer_t
a type for a number (integer)
Definition json.hpp:1479
@ value
the parser finished reading a JSON value
a class to store JSON values
Definition json.hpp:1040
basic_json<> json
default JSON class
Definition json.hpp:12369

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 3315 of file json.hpp.