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>
reference nlohmann::basic_json::operator+= ( basic_json &&  value)
inline

add an object to an array Appends the given element value to the end of the JSON value. If the function is called on a JSON null value, an empty array is created before appending value.

Parameters
valuethe value to add to the JSON array
Exceptions
std::domain_errorwhen called on a type other than JSON array or null
Complexity
Amortized constant.
Example
The example shows how push_back and += can be used to add elements to a JSON array. Note how the null value was silently converted to a JSON array.
1 #include <json.hpp>
2 
3 using namespace nlohmann;
4 
5 int main()
6 {
7  // create JSON values
8  json array = {1, 2, 3, 4, 5};
9  json null;
10 
11  // print values
12  std::cout << array << '\n';
13  std::cout << null << '\n';
14 
15  // add values
16  array.push_back(6);
17  array += 7;
18  null += "first";
19  null += "second";
20 
21  // print values
22  std::cout << array << '\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):
[1,2,3,4,5]
null
[1,2,3,4,5,6,7]
["first","second"]
The example code above can be translated with
g++ -std=c++11 -Isrc doc/examples/push_back.cpp -o push_back