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Updated for v4.0

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Benoit Blanchon
2014-11-11 14:26:57 +01:00
parent dfac1cf71a
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README.md
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@ -10,31 +10,48 @@ It has been written with Arduino in mind, but it isn't linked to Arduino librari
Features
--------
* JSON decoding: [see documentation here](/JsonParser/)
* JSON encoding: [see documentation here](/JsonGenerator/)
* JSON decoding
* JSON encoding (with optional indentation)
* Elegant API, very easy to use
* Fixed memory allocation (no malloc)
* Small footprint
* MIT License
Feature comparison
------------------
Quick start
-----------
| Library | Memory allocation | Nested objects | Parser size | Encoder size |
| ------------ | ----------------- | -------------- | ----------- | ------------- |
| Arduino JSON | static | yes | 2760 Bytes | 862 bytes |
| json-arduino | dynamic | no | 3348 (+21%) | not supported |
| aJson | dynamic | yes | 5088 (+84%) | 4678 (+540%) |
#### Decoding / Parsing
char json[] = "{\"sensor\":\"gps\",\"time\":1351824120,\"data\":[48.756080,2.302038]}";
"Parser size" was measured with a program parsing `{"sensor":"outdoor","value":25.6}`.
For each library, I wrote a program that extracts a string and a float. I subtracted the size of a program doing the same without any JSON parsing involved. [Source files are here](https://gist.github.com/bblanchon/e8ba914a7109f3642c0f).
StaticJsonBuffer<200> jsonBuffer;
"Encoder size" was measured with a program generating `{"sensor":"outdoor","value":25.6}`.
[Source files are here](https://gist.github.com/bblanchon/60224e9dcfeab4ddc7e9).
JsonObject& root = jsonBuffer.parseObject(json);
In each case the target platform was an Arduino Duemilanove and Arduino IDE 1.0.5 was used.
const char* sensor = root["sensor"];
long time = root["time"];
double latitude = root["data"][0];
double longitude = root["data"][1];
Links: [json-arduino](https://github.com/not404/json-arduino), [aJson](https://github.com/interactive-matter/aJson)
[See complete guide](/doc/Decoding JSON.md)
#### Encoding / Generating
StaticJsonBuffer<200> jsonBuffer;
JsonObject& root = jsonBuffer.createObject();
root["sensor"] = "gps";
root["time"] = 1351824120;
JsonArray& data = root.createNestedArray("data");
data.add(48.756080, 6); // 6 is the number of decimals to print
data.add(2.302038, 6); // if not specified, 2 digits are printed
root.printTo(Serial);
// This prints:
// {"sensor":"gps","time":1351824120,"data":[48.756080,2.302038]}
[See complete guide](/doc/Encoding JSON.md)
Testimonials
------------
@ -48,11 +65,3 @@ From Arduino's Forum user `gbathree`:
From StackOverflow user `thegreendroid`:
> It has a really elegant, simple API and it works like a charm on embedded and Windows/Linux platforms. We recently started using this on an embedded project and I can vouch for its quality.
Related blog posts
-----
* [The project I originally wrote this library for](http://blog.benoitblanchon.fr/rfid-payment-terminal/)
* [Motivation for this library](http://blog.benoitblanchon.fr/arduino-json-parser/)
* [Release of version 2](http://blog.benoitblanchon.fr/arduino-json-v2-0/)
* [Release of version 3](http://blog.benoitblanchon.fr/arduino-json-v3-0/)