Numeric Variable Type Conversions

william chan

Hi,

I can't find any type-conversion (type-casting) commands in SPIN.

1. What happens when we assign a byte value to a long variable?
Will the value be preserved?

2. When we assign a word variable with a value in a long variable?

3. What happens if a procedure requires a byte parameter, but instead we supply it with a long?

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deSilva

In SPIN there is hardly any "magic" - it's genarally the most simple you can imagine!

(1) The sign will not be extended, there is a specific operator if you need that: ~
(2) The sign will not be extended, there is a specific operator if you need that: ~~
(3) This - again - is a nonsense question

jazzed

On 3: Parameters to methods are like void* parameters in C.
You can cast with byte, word, and long. You get lots of "flexibility" here; don't hurt yourself.

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Mike Green

On 3: All parameters and local variables are implicitly declared as longs. If you pass a byte value, ordinary assignment rules will apply ... the byte value will be zero extended to make a long value.

jazzed

Mmm. Yea, C does tend to sign extend whatever is in the MSB unless you cast it "correctly" [noparse]:)[/noparse] C void* generally follows the natural width of the architecture unless overriden as is possible in mips64 for example. But ... you have to know C to understand that ... as most of us do.· ADDED: Fair clarification of course Mike.

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Post Edited (jazzed) : 3/7/2008 12:11:32 AM GMT