Re: Beginner's question (array parameters to functions)

[fjh@cs.mu.oz.au (Fergus Henderson)]

Matthew Heaney <matthew_heaney@acm.org> writes:

 >fjh@cs.mu.oz.au (Fergus Henderson) writes:
 >
 >> Matthew Heaney <matthew_heaney@acm.org> writes:
 >> 
 >> >greg <ref15@columbia.edu> writes:
 >> >> One requirement of the assignment is that the
 >> >> sorting be done by a function which takes the array as a parameter and
 >> >> returns a sorted array.
 >> ...
 >> >> is there some way to avoid having to use two arrays?
...
 >> >Having two arrays is a condition of the problem statement,
 >> >and has nothing to do with the language.
 >> 
 >> This is not correct.
 >> 
 >> In some languages, e.g. C++, arrays can be passed and returned by
 >> reference, and can be modified, so (unless there was some additional
 >> constraint in the assignment, e.g. that the function's input argument
 >> not be modified) the two arrays could be the same array.
 >
 >That is precisely that case.  The requirement is for a function, not a
 >procedure.  Therefore, there is a requirement that the original array
 >not be modified.

That conclusion ("Therefore, ...") may be true if you restrict yourself to
Ada.  But there are other languages for which it is not true, as I
demonstrated by the examples in my reply.  Thus your statement that
"it has nothing to do with the language" is not correct.

 >> The fact that these two arrays have different contents is not a contraction,
 >> because the different contents occur at different times, and it's quite
 >> possible for a single array to have different contents at different times.
 >
 >I don't understand this paragraph.

Sorry -- I meant to write "contradiction" instead of "contraction".

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