# Sparkplug: How to deal with negative signed integers?

**URL:** https://community.hivemq.com/t/sparkplug-how-to-deal-with-negative-signed-integers/463
**Category:** Sparkplug
**Created:** [March 17, 2021, 8:08am UTC](https://community.hivemq.com/t/sparkplug-how-to-deal-with-negative-signed-integers/463 "2021-03-17T08:08:36Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![nhosko](https://avatars.discourse-cdn.com/v4/letter/n/34f0e0/32.png) [@nhosko](https://community.hivemq.com/u/nhosko)
#### Post date: [March 17, 2021, 8:08am UTC](https://community.hivemq.com/t/sparkplug-how-to-deal-with-negative-signed-integers/463/1 "2021-03-17T08:08:36Z")

</div>

On the sparkplug protocol there are the following “Basic types” defined:

```
    // Basic Types
    Int8 = 1;
    Int16 = 2;
    Int32 = 3;
    Int64 = 4;
    UInt8 = 5;
    UInt16 = 6;
    UInt32 = 7;
    UInt64 = 8;
    Float = 9;
    Double = 10;
    Boolean = 11;
    String = 12;
    DateTime = 13;
    Text = 14;

```

However, inside the message Metric definition, the (signed) integers are ignored and only the unsigned integer from GoogleProtobuf are used for dealing with int\_value and long\_value inside the “oneof value” part:

```
message Metric {
    # Other defs removed for clearness
    oneof value {
        uint32 int_value = 10;
        uint64 long_value = 11;
        float float_value = 12;
        double double_value = 13;
        bool boolean_value = 14;
        string string_value = 15;
        bytes bytes_value = 16; // Bytes, File
        DataSet dataset_value = 17;
        Template template_value = 18;
        MetricValueExtension extension_value = 19;
    }
}

```

On [Protocol Buffers - Scalar Value Types](https://developers.google.com/protocol-buffers/docs/proto#scalar) the .proto Type “uint32/64” is equivalent to “uint32/64” of C++, this means that I’m not able to use C++ signed integers (int32/64) directly on Sparkplug.

What “oneof value” should I use for transferring negative signed integers (C++type = int32/64) on Sparkplug?

---

<div class="post-metadata">

### Author: ![nhosko](https://avatars.discourse-cdn.com/v4/letter/n/34f0e0/32.png) [@nhosko](https://community.hivemq.com/u/nhosko)
#### Post date: [March 17, 2021, 10:09am UTC](https://community.hivemq.com/t/sparkplug-how-to-deal-with-negative-signed-integers/463/2 "2021-03-17T10:09:27Z")

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I’m now able to transfer negative numbers on my payload.

Here what I’ve done

1. Set the metric.datatype correctly, e.g. INT32
2. Cast the INT32 Value, for example “-32” to UINT32, e.g. “4294967264”
3. Add the converted value as metric.int\_value
4. Send via MQTT
5. On MQTTFx the Sparkplug Decoder shows the “-32”:  
`{"timestamp":1607590027225,"metrics":[{"name":"MyINT32","timestamp":1607590027225,"dataType":"Int32","value":-32}],"seq":0}`

Is this the way to go?

Would it not be better to have the following Message Metric definition?

```
message Metric {
    # Other defs removed for clearness
    oneof value {
        sint32 sint_value = 10;
        sint64 slong_value = 11;
        uint32 uint_value = 12;
        uint64 ulong_value = 13;
        float float_value = 14;
        double double_value = 15;
        bool boolean_value = 16;
        string string_value = 17;
        bytes bytes_value = 18; // Bytes, File
        DataSet dataset_value = 19;
        Template template_value = 20;
        MetricValueExtension extension_value = 21;
    }
}
```

---

<div class="post-metadata">

### Author: ![SShet](https://avatars.discourse-cdn.com/v4/letter/s/b3f665/32.png) [@SShet](https://community.hivemq.com/u/SShet)
#### Post date: [March 18, 2021, 1:50pm UTC](https://community.hivemq.com/t/sparkplug-how-to-deal-with-negative-signed-integers/463/3 "2021-03-18T13:50:27Z")

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Hello nhosko

Thanks for reaching out. Nice to see that you’re taking interest in Sparkplug.

Your solution to transfer negative numbers looks good.

Thanks & Regards,  
Sheetal from the HiveMQ Team