JSON for Modern C++ 2.1.1

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
begin
begin
boolean_t
cbegin
cend
clear
const_iterator
const_pointer
const_reference
const_reverse_iterator
count
crbegin
crend
detail::external_constructor
diff
difference_type
dump
emplace
emplace_back
empty
end
end
erase
erase
erase
erase
exception
find
find
flatten
from_cbor
from_msgpack
front
front
get
get
get
get
get
get_allocator
get_ptr
get_ptr
get_ref
get_ref
insert
insert
insert
insert
insert
insert
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
iterator
iterator_wrapper
iterator_wrapper
json_serializer
max_size
meta
number_float_t
number_integer_t
number_unsigned_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>
operator>
operator>=
operator>=
operator>=
operator>>
operator>>
operator[]
operator[]
operator[]
operator[]
operator[]
operator[]
operator[]
operator[]
operator[]
operator[]
other_error
out_of_range
parse
parse
parse
parse
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
size
size_type
string_t
swap
swap
swap
swap
to_cbor
to_msgpack
type
type_error
type_name
unflatten
value
value
value
value
value_t
value_type
~basic_json
| ## ◆ operator[]() [4/10] 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>
const_reference nlohmann::basic_json::operator[] | ( | const typename object_t::key_type & | key | ) | const
| inline
  Returns a const reference to the element at with specified key key. No bounds checking is performed. Warning If the element with key key does not exist, the behavior is undefined. Parameters
  [in] | key | key of the element to access
  Returns const reference to the element at key key Precondition The element with key key must exist. This precondition is enforced with an assertion. Exceptions
  type_error.305 | if the JSON value is not an object; in that cases, using the [] operator with a key makes no sense.
  Complexity Logarithmic in the size of the container. Example The example below shows how object elements can be read using the `[]` operator. 1 #include "json.hpp" 2 3 using json = nlohmann::json; 4 5 int main() 6 { 7 // create a JSON object 8 const json object = 9 { 10 {"one", 1}, {"two", 2}, {"three", 2.9} 11 }; 12 13 // output element with key "two" 14 std::cout << object["two"] << '\n'; 15 } nlohmann::json basic_json<> json default JSON class Definition: json.hpp:13933 Output (play with this example online):
      2
  The example code above can be translated with
      g++ -std=c++11 -Isrc doc/examples/operatorarray__key_type_const.cpp -o operatorarray__key_type_const
See also at(const typename object_t::key_type&) for access by reference with range checking value() for access by value with a default value Since version 1.0.0 Definition at line 4116 of file json.hpp.