JSON for Modern C++  3.7.0

◆ swap() [3/4]

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>
void nlohmann::basic_json::swap ( object_t other)
inline

Exchanges the contents of a JSON object with those of other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated.

Parameters
[in,out]otherobject to exchange the contents with
Exceptions
type_error.310when JSON value is not an object; example: "cannot use swap() with string"
Complexity
Constant.
Example
The example below shows how objects can be swapped with swap().
1 #include <iostream>
2 #include <nlohmann/json.hpp>
3 
4 using json = nlohmann::json;
5 
6 int main()
7 {
8  // create a JSON value
9  json value = { {"translation", {{"one", "eins"}, {"two", "zwei"}}} };
10 
11  // create an object_t
12  json::object_t object = {{"cow", "Kuh"}, {"dog", "Hund"}};
13 
14  // swap the object stored in the JSON value
15  value["translation"].swap(object);
16 
17  // output the values
18  std::cout << "value = " << value << '\n';
19  std::cout << "object = " << object << '\n';
20 }
basic_json<> json
default JSON class
Definition: json.hpp:2355
ObjectType< StringType, basic_json, object_comparator_t, AllocatorType< std::pair< const StringType, basic_json > >> object_t
a type for an object
Definition: json.hpp:14889
ValueType value(const typename object_t::key_type &key, const ValueType &default_value) const
access specified object element with default value
Definition: json.hpp:17829

Output (play with this example online):
value = {"translation":{"cow":"Kuh","dog":"Hund"}}
object = {"one":"eins","two":"zwei"}
The example code above can be translated with
g++ -std=c++11 -Isingle_include doc/examples/swap__object_t.cpp -o swap__object_t 
Since
version 1.0.0

Definition at line 19945 of file json.hpp.