Passing arrays to methods?

Question

Hi all,
Thanks to most of the main contributors in this forum nearly all of my major hurdles in transitioning from proc-C to Cocoa have been overcome. However, while I was shown how to use NSMutableArray in conjunction with NSDictionary to do pretty much the same job as a C-style multi-dimensional array, dictionaries aren't always the perfect solution in every situation. So, let's suppose I wanted to construct a pure Cocoa facsimile of a C-style [4][x] array like this...
NSArray *replicaArray = [NSArray arrayWithObjects:
[NSNull null], // index 0 (unused)
[NSMutableArray array], // index 1
[NSMutableArray array], // index 2
[NSMutableArray array],nil]; // index 3
I threw in an NSNull as the first array object because (whenever possible) I adopted the habit of leaving row0 and column0 of multidimensional arrays unused to make for more natural, readable iteration ops and stuff. The above code works perfectly well, but with 4-5 different arrays in the same proc-C apps I often had to pass them to common functions (to handle things like bubble-sorting etc.) like the one below:
void bubbleSortSimpleArray (short arry[ ], short numsToSort)
short ctr,loopCtr,storeValue;
for (loopCtr = 1; loopCtr <= numsToSort; loopCtr++)
ctr = 1;
while (ctr < numsToSort)
if (arry[ctr] > arry[ctr+1])
storeValue = arry[ctr+1];
arry[ctr+1] = arry[ctr];
arry[ctr] = storeValue;
++ctr;
Of course, thanks to the advantages of Cocoa this entire code block can be replaced in just a couple lines with 'sortUsingSelector'. Sorry for the lengthy outline in attempting to describe my problem as clearly as possible , but (finally) _is it possible to pass arrays to methods_ in our Cocoa code in a similar way? I was thinking something along the lines of:
- (void)doMoreProcessing:(id)array
//do some other common stuff on my array(s) here...
That'd simplify converting some of my old code and be a real bonus for me, but I haven't been able to find any reference about this on the net so far, and experimenting with my code hasn't provided me with any answers yet, either... Any guidance on this would be very much appreciated!
Thanks in advance.
Ernie

Answer 1

Hi Bang A. Lore,
Thanks for your input but I've got it figured out now However, while you quite correctly say:
Pointers work the same way as they do in C.
the cause of my problems wasn't a lack of understanding of pointers, but by the syntax differences between proc-C and obj-C. I'm well aware of the fact that the name of a passed array is just a pointer to its address in memory of course, but attempting to use a mandatory 'C' style header declaration along the lines of:
- (void)test2DArray:(NSMutableArray*)array[][];
just kept giving me parse errors, as did any attempt to use square brackets in the implementation file. While 'C' insists on using them, I found (after some more experimentation) that obj-C will quite happily accept:
- (void)test2DArray:(NSMutableArray*)array;
...or the even simpler...
- (void)test2DArray:(id)array;
Also pleasantly surprised to find that Cocoa doesn't seem to give a hoot whether the (array) object you pass it is flat OR multidimensional -- whereas 'C' insists you even provide the called function with the number of rows contained in a multi-subscripted array -- which often meant I had to include two versions of many functions containing identical code, depending on whether they were called by 1D or 2D arrays.
Once I hit on the idea of omitting the square brackets entirely (just to stop the darned parse errors and see what would happen out of curiosity), the problem just went away.
Thanks once again. Appreciate it!