operator[]() [1/8]

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, class BinaryType = std::vector<std::uint8_t>>

reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator[] ( const json_pointer &  ptr )

inline

access specified element via JSON Pointer

Uses a JSON pointer to retrieve a reference to the respective JSON value. No bound checking is performed. Similar to operator[](const typename object_t::key_type&), null values are created in arrays and objects if necessary.

In particular:

• If the JSON pointer points to an object key that does not exist, it is created an filled with a null value before a reference to it is returned.
• If the JSON pointer points to an array index that does not exist, it is created an filled with a null value before a reference to it is returned. All indices between the current maximum and the given index are also filled with null.
• The special value - is treated as a synonym for the index past the end.

Parameters

[in]

ptr

a JSON pointer

Returns

reference to the element pointed to by ptr

@complexity Constant.

Exceptions

parse_error.106	if an array index begins with '0'
parse_error.109	if an array index was not a number
out_of_range.404	if the JSON pointer can not be resolved

@liveexample{The behavior is shown in the example.,operatorjson_pointer}

Since

version 2.0.0

Definition at line 25917 of file json.hpp.

    {
        return ptr.get_unchecked(this);
    }