JSON for Modern C++  3.7.3

◆ update() [1/2]

void nlohmann::basic_json::update ( const_iterator  first,
const_iterator  last 
)
inline

Inserts all values from from range [first, last) and overwrites existing keys.

Parameters
[in]firstbegin of the range of elements to insert
[in]lastend of the range of elements to insert
Exceptions
type_error.312if called on JSON values other than objects; example: "cannot use update() with string"
invalid_iterator.202if iterator first or last does does not point to an object; example: "iterators first and last must point to objects"
invalid_iterator.210if first and last do not belong to the same JSON value; example: "iterators do not fit"
Complexity
O(N*log(size() + N)), where N is the number of elements to insert.
Example
The example shows how update() is used__range.
1 #include <iostream>
2 #include <iomanip>
3 #include <nlohmann/json.hpp>
4 
5 using json = nlohmann::json;
6 
7 int main()
8 {
9  // create two JSON objects
10  json o1 = R"( {"color": "red", "price": 17.99} )"_json;
11  json o2 = R"( {"color": "blue", "speed": 100} )"_json;
12 
13  // add all keys from o2 to o1 (updating "color")
14  o1.update(o2);
15 
16  // output updated object o1
17  std::cout << std::setw(2) << o1 << '\n';
18 }

Output (play with this example online):
{
  "color": "blue",
  "price": 17.99,
  "speed": 100
}
The example code above can be translated with
g++ -std=c++11 -Isingle_include doc/examples/update.cpp -o update 
See also
https://docs.python.org/3.6/library/stdtypes.html#dict.update
Since
version 3.0.0

Definition at line 20013 of file json.hpp.

nlohmann::json
basic_json<> json
default JSON class
Definition: json.hpp:2445