ABC of arrays

[Mike Bonner]

I'm one who uses visualization to get a handle on things like arrays.  For
me, arrays are just a bunch of nested boxes.  And a box can contain other
boxes, or a dataitem, but not both.

So if you get the keys of myArray you've just looked into the first box to
see whats there. If there are no keys in myArray of course, its not array,
and must be empty, or contain a data item.
If there are keys, those are just other boxes, and you must specifically
open each box to see whats inside it. the keys of myArray["box1"] might
contain a data item, or more boxes. (and since square brackets are used, it
actually reinforces my mental picture of little boxes all the same)

On Wed, Apr 1, 2015 at 3:19 PM, Michael Doub <mikedoub at gmail.com> wrote:

> Graham,
>
> I think one of the things that is confusing you as you are trying to learn
> arrays is the fact that you are looking at output created by
> ConvertXMLToArray.   ConvertXMLToArray is working as designed, but it just
> happens to create key in a syntax that looks like a livecode array
> reference.    LiveCode keys are just strings, so ConvertXMLToArray is
> adding a open bracket, a counter, and a close bracket when it sees
> multiples of a xml tag, to make it unique within the array.
>
> This makes perfect sense technically but I can see where it could really
> confuse someone trying to figure out livecode arrays.
>
> -= Mike
>
>
>
>
> On 4/1/15 3:48 PM, Graham Samuel wrote:
>
>> Well, Richard, I am always very willing to believe that I’ve
>> misunderstood something, but this is what happened (this material is
>> extracted from conversations I had on this list in the middle of March).
>>
>> 1. I had an XML file - it was actually a .gpx file, which shows a
>> geographical route as a series of waypoints. The ‘top level’ of this
>> structure is ‘gpx’. I mean the first three lines are (watch for wordwrap):
>>
>> <?xml version="1.0" encoding="UTF-8"?>
>> <gpx xmlns="http://www.topografix.com/GPX/1/1" creator="Geolives"
>> version="1.1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>> xsi:schemaLocation="http://www.topografix.com/GPX/1/1
>> http://www.topografix.com/GPX/1/1/gpx.xsd">
>>    <metadata />
>>    <trk>
>>
>> 2. I converted it to an array using the function ConvertXMLToArray, by
>> Trevor deVore - from Mike Doub’s Master Library.
>>
>> 3. I put the result into an array called ‘gGeneralArray’ - I can see this
>> in the IDE as a nested structure.
>>
>> 4. I executed
>>
>>    put the keys of gGeneralArray
>>
>> in the message box, and got the result
>>
>>   gpx
>>
>> 5. I discussed this on the use-list, and Mike Bonner suggested
>>
>>  try
>>> put the keys of gGeneralArray["gpx”]
>>> and you'll get the next level of keys.
>>>
>> 6. I did that and got
>>
>> wpt[1]
>> trk
>> @attributes
>> wpt[4]
>> wpt[2]
>> metadata
>> wpt[3]
>>
>> I just did this all again to prove to myself that I hadn’t made an
>> obvious error.I am definitely only dealing with one array, so I can’t
>> explain this, and the LC dictionary certainly doesn’t help.
>>
>> Tell me where I went wrong!
>>
>> Graham
>>
>>  On 1 Apr 2015, at 18:27, Richard Gaskin <ambassador at fourthworld.com>
>>> wrote:
>>>
>>> Graham Samuel wrote:
>>>
>>>> And some things are just wrong: for example the very simple statement
>>>>
>>>> put the keys of myArray
>>>>
>>>> may or may not list all the keys, or it may.  I have never understood
>>>> this, especially as the Dictionary doesn’t discuss such ambiguities.
>>>>
>>> The Dictionary doesn't describe that because it should never happen.
>>>
>>> Under what circumstances would "the keys" not returns the keys?
>>>
>>> FWIW, I've only seen "the keys" return all keys in every version of
>>> LC/MC I've ever used.
>>>
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