nlohmannjson/docs/index.md

nlohmann::basic_json

Defined in header <json.hpp>

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 Allocator = std::allocator
> class basic_json;

Template Parameters

• ObjectType - The type to store collection of name/value pairs. It can be any associative container that can hold key-value pairs as long as the key type is the same as StringType. The value type is again nlohmann::basic_json. The parameter ObjectType defaults to std::map.
• ArrayType - The type to store ordered value lists. It can be any sequence container. The parameter ArrayType defaults to a std::vector whose elements are of type nlohmann::basic_json.
• StringType - The type to store string values. The parameter StringType defaults to std::string.
• BooleanType
• NumberIntegerType
• NumberFloatType
• Allocator - An allocator that is used to acquire memory to store the elements. The type must meet the requirements of Allocator.

Specializations

A standard JSON type nlohmann::json is defined in <json.hpp> which uses the default types:

using json = basic_json<
    std::map,
    std::vector,
    std::string,
    bool,
    int64_t,
    double,
    std::allocator
>

Iterator invalidation

Member types

• value_type
• reference
• const_reference
• difference_type
• size_type
• allocator_type
• pointer
• const_pointer
• iterator
• const_iterator
• reverse_iterator
• const_reverse_iterator
• object_t
• array_t
• string_t
• boolean_t
• number_integer_t
• number_float_t
• list_init_t
• json_value

Member functions

• constructor
• destructor
• operator=
• get_allocator

Object inspection

• dump
• type
• is_null
• is_boolean
• is_number
• is_object
• is_array
• is_string
• operator value_t
• std::hash

Value conversion

• get
• implicit conversion

Element access

• at
• operator[]
• erase
• find
• count

Iterators

• begin / cbegin
• end / cend
• rbegin / crbegin
• rend / crend

Capacity

• empty
• size
• max_size

Modifiers

• clear
• push_back
• operator+=
• erase
• swap
• std::swap

Comparisons

• operator==
• operator!=
• operator<
• operator<=
• operator>
• operator>=

Serialization

• dump
• operator<<
• operator>>

Deserialization

• parse
• operator<<
• operator>>