operator[]() [6/8]

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>>

const_reference nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::operator[] ( size_type  idx ) const

inline

access specified array element

Returns a const reference to the element at specified location idx.

Parameters

[in]

idx

index of the element to access

Returns

const reference to the element at index idx

Exceptions

type_error.305

if the JSON value is not an array; in that case, using the [] operator with an index makes no sense.

@complexity Constant.

@liveexample{The example below shows how array elements can be read using the [] operator.,operatorarray__size_type_const}

Since

version 1.0.0

Definition at line 21437 of file json.hpp.

    {
        // const operator[] only works for arrays
        if (JSON_HEDLEY_LIKELY(is_array()))
        {
            return m_value.array->operator[](idx);
        }
 
        JSON_THROW(type_error::create(305, "cannot use operator[] with a numeric argument with " + std::string(type_name()), *this));
    }