Arrays

brs

i haven't been able to try this yet (still waiting on my propeller shipment), but i was wondering if it's possible to pass arrays in/out of methods?

for example, if "a" is an array, "fido" is the object name, and "Catch" is a public method of "fido" then would the calling statement be: fido.catch(@a)?

i'm presuming references are used to pass arrays around, but i'm uncertain about the syntax used to dereference the arrays once they are passed into or out of a method or if this is even possible?

regards,
bryce

Jon Williams

Using @ is passing the address of, so yes, you can use this to pass the starting address of an array -- you could actually pass the address of an element within the array as well. The method receiving this parameter should know that it's getting an address and not a value.

Passing the address of a variable (or block of them) is useful for letting one process (cog) update variables for another -- one process simply passes the address of the variable(s) it wants the other to have access to. This is possible because all Spin variables reside in main RAM.

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Jon Williams
Applications Engineer, Parallax

brs

here is a very simple example (please see attached files).

test.spin contains the "Main" public method that initializes array "a" and passes it into the "fido.Catch" method as a pointer or reference. the arrays i wish to use contain floating-point numbers.

the "a" array will then be manipulated to obtain another array, let's call it "b", and this will be passed out of the method back to "Main".

i finally obtained my propeller, but debugging does not yield the expected results. i don't think i'm dereferencing the arrays correctly!

any ideas?

Post Edited (brs) : 5/15/2006 3:37:15 AM GMT

brs

does anyone have a quick example of passing an array of either integer or floating-point values into a method, manipulate those values, and then pass an array back out?

cgracey

I think I fixed your code. Try these.

brs said...
here is a very simple example (please see attached files).

test.spin contains the "Main" public method that initializes array "a" and passes it into the "fido.Catch" method as a pointer or reference. the arrays i wish to use contain floating-point numbers.

the "a" array will then be manipulated to obtain another array, let's call it "b", and this will be passed out of the method back to "Main".

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Chip Gracey
Parallax, Inc.

brs

Thanks Chip. I'll give it a shot tonight.

Could you please explain the significance of declaring b[noparse][[/noparse]20] as a variable in the fido.spin file. why make this a permanent variable?