JSON for Modern C++ 2.1.1
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◆ push_back() [1/4]

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< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer >::push_back ( basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer > &&  val)
inline

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

Parameters
[in]valthe value to add to the JSON array
Exceptions
std::domain_errorwhen called on a type other than JSON array or null; example: "cannot use push_back() with number"
Complexity\n Amortized constant.
Example\n 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
3using json = nlohmann::json;
4
5int 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
17 array += 7;
18 null += "first";
19 null += "second";
20
21 // print values
22 std::cout << array << '\n';
23 std::cout << null << '\n';
24}
static basic_json array(std::initializer_list< basic_json > init=std::initializer_list< basic_json >())
explicitly create an array from an initializer list
Definition json.hpp:2165
void push_back(basic_json &&val)
add an object to an array
Definition json.hpp:5258
a class to store JSON values
Definition json.hpp:1040
basic_json<> json
default JSON class
Definition json.hpp:12369

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 
Since
version 1.0.0

Definition at line 5258 of file json.hpp.