[Newbies] Storing a negative SmallInterger in a ByteArray

Lukas Renggli renggli at gmail.com
Mon Mar 5 10:48:13 UTC 2007

> I am a bit confused...
> I am working on an implementation to communicate with the Lego
> Mindstorms NXT. Al works fine, except I have to store some negative
> numbers in the ByteArray that should be send to the NXT. Everytime I
> try, I get an improper store into indexable object.

The elements of a ByteArray are unsigned bytes, a value between 0 and 255.

> Is it possible to store negative values in a ByteArray?

There are several helper methods implemented in ByteArray. Have a look
at the code I sent you, the NxtConnection>>#send: primitive makes use
of these methods:

    doubleAt: index put: value bigEndian: bool
    longAt: index put: value bigEndian: aBool
    shortAt: index put: value bigEndian: aBool
    unsignedLongAt: index put: value bigEndian: aBool
    unsignedShortAt: index put: value bigEndian: aBool


Lukas Renggli

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