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

std::ostream & operator<< ( std::ostream &  o, const basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType > &  j  )

friend

serialize to stream

Serialize the given JSON value j to the output stream o. The JSON value will be serialized using the dump member function.

• The indentation of the output can be controlled with the member variable width of the output stream o. For instance, using the manipulator std::setw(4) on o sets the indentation level to 4 and the serialization result is the same as calling dump(4).
• The indentation character can be controlled with the member variable fill of the output stream o. For instance, the manipulator ‘std::setfill(’\t')` sets indentation to use a tab character rather than the default space character.

Parameters

[in,out]	o	stream to serialize to
[in]	j	JSON value to serialize

Returns

the stream o

Exceptions

type_error.316

if a string stored inside the JSON value is not UTF-8 encoded

@complexity Linear.

@liveexample{The example below shows the serialization with different parameters to width to adjust the indentation level.,operator_serialize}

Since

version 1.0.0; indentation character added in version 3.0.0

Definition at line 24515 of file json.hpp.

    {
        // read width member and use it as indentation parameter if nonzero
        const bool pretty_print = o.width() > 0;
        const auto indentation = pretty_print ? o.width() : 0;
        // reset width to 0 for subsequent calls to this stream
        o.width(0);
        // do the actual serialization
        serializer s(detail::output_adapter<char>(o), o.fill());
        s.dump(j, pretty_print, false, static_cast<unsigned int>(indentation));
        return o;
    }