75 lines
2.5 KiB
C++
75 lines
2.5 KiB
C++
// ArduinoJson - arduinojson.org
|
|
// Copyright Benoit Blanchon 2014-2018
|
|
// MIT License
|
|
//
|
|
// This example shows the different ways you can use String with ArduinoJson.
|
|
//
|
|
// Use String objects sparingly, because ArduinoJson duplicates them in the
|
|
// JsonBuffer. Prefer plain old char[], as they are more efficient in term of
|
|
// code size, speed, and memory usage.
|
|
|
|
#include <ArduinoJson.h>
|
|
|
|
void setup() {
|
|
DynamicJsonBuffer jsonBuffer;
|
|
|
|
// You can use a String as your JSON input.
|
|
// WARNING: the content of the String will be duplicated in the JsonBuffer.
|
|
String input =
|
|
"{\"sensor\":\"gps\",\"time\":1351824120,\"data\":[48.756080,2.302038]}";
|
|
JsonObject& root = jsonBuffer.parseObject(input);
|
|
|
|
// You can use a String to get an element of a JsonObject
|
|
// No duplication is done.
|
|
long time = root[String("time")];
|
|
|
|
// You can use a String to set an element of a JsonObject
|
|
// WARNING: the content of the String will be duplicated in the JsonBuffer.
|
|
root[String("time")] = time;
|
|
|
|
// You can get a String from a JsonObject or JsonArray:
|
|
// No duplication is done, at least not in the JsonBuffer.
|
|
String sensor = root["sensor"];
|
|
|
|
// Unfortunately, the following doesn't work (issue #118):
|
|
// sensor = root["sensor"]; // <- error "ambiguous overload for 'operator='"
|
|
// As a workaround, you need to replace by:
|
|
sensor = root["sensor"].as<String>();
|
|
|
|
// You can set a String to a JsonObject or JsonArray:
|
|
// WARNING: the content of the String will be duplicated in the JsonBuffer.
|
|
root["sensor"] = sensor;
|
|
|
|
// It works with RawJson too:
|
|
root["sensor"] = RawJson(sensor);
|
|
|
|
// You can also concatenate strings
|
|
// WARNING: the content of the String will be duplicated in the JsonBuffer.
|
|
root[String("sen") + "sor"] = String("gp") + "s";
|
|
|
|
// You can compare the content of a JsonObject with a String
|
|
if (root["sensor"] == sensor) {
|
|
// ...
|
|
}
|
|
|
|
// Lastly, you can print the resulting JSON to a String
|
|
String output;
|
|
root.printTo(output);
|
|
}
|
|
|
|
void loop() {
|
|
// not used in this example
|
|
}
|
|
|
|
// See also
|
|
// --------
|
|
//
|
|
// https://arduinojson.org/ contains the documentation for all the functions
|
|
// used above. It also includes an FAQ that will help you solve any problem.
|
|
//
|
|
// The book "Mastering ArduinoJson" contains a quick C++ course that explains
|
|
// how your microcontroller stores strings in memory. On several occasions, it
|
|
// shows how you can avoid String in your program.
|
|
// Learn more at https://arduinojson.org/book/
|
|
// Use the coupon code TWENTY for a 20% discount ❤❤❤❤❤
|