JSON for Modern C++  3.0
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 AllocatorType = std::allocator>
void nlohmann::basic_json::push_back ( const typename object_t::value_type &  value)
inline

Inserts the given element value to the JSON object. If the function is called on a JSON null value, an empty object is created before inserting value.

Parameters
valuethe value to add to the JSON object
Exceptions
std::domain_errorwhen called on a type other than JSON object or null
Complexity
Logarithmic in the size of the container, O(log(size())).
Example
The example shows how push_back and += can be used to add elements to a JSON object. Note how the null value was silently converted to a JSON object.
1 #include <json.hpp>
2 
3 using namespace nlohmann;
4 
5 int main()
6 {
7  // create JSON values
8  json object = {{"one", 1}, {"two", 2}};
9  json null;
10 
11  // print values
12  std::cout << object << '\n';
13  std::cout << null << '\n';
14 
15  // add values
16  object.push_back(json::object_t::value_type("three", 3));
17  object += json::object_t::value_type("four", 4);
18  null += json::object_t::value_type("A", "a");
19  null += json::object_t::value_type("B", "b");
20 
21  // print values
22  std::cout << object << '\n';
23  std::cout << null << '\n';
24 }
a class to store JSON values
Definition: json.hpp:130
namespace for Niels Lohmann
Definition: json.hpp:55
void push_back(basic_json &&value)
add an object to an array
Definition: json.hpp:3615
Output (play with this example online):
{"one":1,"two":2}
null
{"four":4,"one":1,"three":3,"two":2}
{"A":"a","B":"b"}
The example code above can be translated with
g++ -std=c++11 -Isrc doc/examples/push_back__object_t__value.cpp -o push_back__object_t__value