JSON for Modern C++ 3.7.1

accept
accept
allocator_type
array
array_t
at
at
at
at
at
at
back
back
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_iterator
const_pointer
const_reference
const_reverse_iterator
contains
contains
count
crbegin
crend
detail::external_constructor
diff
difference_type
dump
emplace
emplace_back
empty
end
end
erase
erase
erase
erase
error_handler_t
exception
find
find
flatten
from_bson
from_bson
from_cbor
from_cbor
from_msgpack
from_msgpack
from_ubjson
from_ubjson
front
front
get
get
get
get
get
get
get_allocator
get_ptr
get_ptr
get_ref
get_ref
get_to
get_to
initializer_list_t
input_format_t
insert
insert
insert
insert
insert
insert
insert_iterator
invalid_iterator
is_array
is_boolean
is_discarded
is_null
is_number
is_number_float
is_number_integer
is_number_unsigned
is_object
is_primitive
is_string
is_structured
items
items
iterator
iterator_wrapper
iterator_wrapper
json_pointer
json_sax_t
json_serializer
max_size
merge_patch
meta
number_float_t
number_integer_t
number_unsigned_t
object
object_comparator_t
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>
operator>
operator>=
operator>=
operator>=
operator>>
operator>>
operator[]
operator[]
operator[]
operator[]
operator[]
operator[]
operator[]
operator[]
other_error
out_of_range
parse
parse
parse_error
parse_event_t
parser_callback_t
patch
pointer
push_back
push_back
push_back
push_back
rbegin
rbegin
reference
rend
rend
reverse_iterator
sax_parse
sax_parse
size
size_type
string_t
swap
swap
swap
swap
to_bson
to_bson
to_bson
to_cbor
to_cbor
to_cbor
to_msgpack
to_msgpack
to_msgpack
to_ubjson
to_ubjson
to_ubjson
type
type_error
type_name
unflatten
update
update
value
value
value
value
value_t
value_type
~basic_json
| ## ◆ get_ref() [2/2] 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 ReferenceType , typename std::enable_if< std::is_reference< ReferenceType >::value and std::is_const< typename std::remove_reference< ReferenceType >::type >::value, int >::type = 0>
ReferenceType nlohmann::basic_json::get_ref | ( |  | ) | const
| inline
  get a reference value (implicit) Implicit reference access to the internally stored JSON value. No copies are made. Warning Writing data to the referee of the result yields an undefined state. Template Parameters
  ReferenceType | reference type; must be a reference to array_t, object_t, string_t, boolean_t, number_integer_t, or number_float_t. Enforced by static assertion.
  Returns reference to the internally stored JSON value if the requested reference type ReferenceType fits to the JSON value; throws type_error.303 otherwise Exceptions
  type_error.303 | in case passed type ReferenceType is incompatible with the stored JSON value; see example below
  Complexity Constant. Example The example shows several calls to `get_ref()`. 1 #include <iostream> 2 #include <nlohmann/json.hpp> 3 4 using json = nlohmann::json; 5 6 int main() 7 { 8 // create a JSON number 9 json value = 17; 10 11 // explicitly getting references 12 auto r1 = value.get_ref<const json::number_integer_t&>(); 13 auto r2 = value.get_ref<json::number_integer_t&>(); 14 15 // print the values 16 std::cout << r1 << ' ' << r2 << '\n'; 17 18 // incompatible type throws exception 19 try 20 { 21 auto r3 = value.get_ref<json::number_float_t&>(); 22 } 23 catch (json::type_error& ex) 24 { 25 std::cout << ex.what() << '\n'; 26 } 27 } Output (play with this example online):
      17 17
      [json.exception.type_error.303] incompatible ReferenceType for get_ref, actual type is number
  The example code above can be translated with
      g++ -std=c++11 -Isingle_include doc/examples/get_ref.cpp -o get_ref
Since version 1.1.0 Definition at line 17380 of file json.hpp.

nlohmann::basic_json::value
ValueType value(const typename object_t::key_type &key, const ValueType &default_value) const
access specified object element with default value
Definition: json.hpp:17966
nlohmann::basic_json::number_integer_t
NumberIntegerType number_integer_t
a type for a number (integer)
Definition: json.hpp:15223
nlohmann::basic_json::number_float_t
NumberFloatType number_float_t
a type for a number (floating-point)
Definition: json.hpp:15362
nlohmann::basic_json::type_error
detail::type_error type_error
exception indicating executing a member function with a wrong type
Definition: json.hpp:14780
nlohmann::json
basic_json<> json
default JSON class
Definition: json.hpp:2445