// 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 void setup() { DynamicJsonDocument doc; // 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]}"; deserializeJson(doc, input); JsonObject obj = doc.as(); // You can use a String to get an element of a JsonObject // No duplication is done. long time = obj[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. obj[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 = obj["sensor"]; // Unfortunately, the following doesn't work (issue #118): // sensor = obj["sensor"]; // <- error "ambiguous overload for 'operator='" // As a workaround, you need to replace by: sensor = obj["sensor"].as(); // You can set a String to a JsonObject or JsonArray: // WARNING: the content of the String will be duplicated in the JsonBuffer. obj["sensor"] = sensor; // It works with serialized() too: obj["sensor"] = serialized(sensor); // You can also concatenate strings // WARNING: the content of the String will be duplicated in the JsonBuffer. obj[String("sen") + "sor"] = String("gp") + "s"; // You can compare the content of a JsonObject with a String if (obj["sensor"] == sensor) { // ... } // Lastly, you can print the resulting JSON to a String String output; serializeJson(doc, output); } void loop() { // not used in this example } // Visit https://arduinojson.org/v6/example/string/ for more.