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ProgmemExample.ino

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  • ProgmemExample.ino 2.03 KiB
    // ArduinoJson - https://arduinojson.org
    // Copyright © 2014-2025, Benoit BLANCHON
    // MIT License
    //
    // This example shows the different ways you can use Flash strings with
    // ArduinoJson.
    //
    // Use Flash strings sparingly, because ArduinoJson duplicates them in the
    // JsonDocument. Prefer plain old char*, as they are more efficient in term of
    // code size, speed, and memory usage.
    //
    // https://arduinojson.org/v7/example/progmem/
    
    #include <ArduinoJson.h>
    
    void setup() {
      JsonDocument doc;
    
      // You can use a Flash String as your JSON input.
      // WARNING: the strings in the input will be duplicated in the JsonDocument.
      deserializeJson(doc, F("{\"sensor\":\"gps\",\"time\":1351824120,"
                             "\"data\":[48.756080,2.302038]}"));
    
      // You can use a Flash String as a key to get a member from JsonDocument
      // No duplication is done.
      long time = doc[F("time")];
    
      // You can use a Flash String as a key to set a member of a JsonDocument
      // WARNING: the content of the Flash String will be duplicated in the
      // JsonDocument.
      doc[F("time")] = time;
    
      // You can set a Flash String as the content of a JsonVariant
      // WARNING: the content of the Flash String will be duplicated in the
      // JsonDocument.
      doc["sensor"] = F("gps");
    
      // It works with serialized() too:
      doc["sensor"] = serialized(F("\"gps\""));
      doc["sensor"] = serialized(F("\xA3gps"), 3);
    
      // You can compare the content of a JsonVariant to a Flash String
      if (doc["sensor"] == F("gps")) {
        // ...
      }
    }
    
    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 memory
    // problem.
    //
    // The book "Mastering ArduinoJson" contains a quick C++ course that explains
    // how your microcontroller stores strings in memory. It also tells why you
    // should not abuse Flash strings with ArduinoJson.
    // Learn more at https://arduinojson.org/book/
    // Use the coupon code TWENTY for a 20% discount ❤❤❤❤❤