[Yaml-core] PHP key order

[<ir...@ms...>]

On Sat, Sep 07, 2002 at 06:52:37PM +0000, Clark C. Evans wrote:
> I have a question about PHP.  It says that it is an "ordered map" but
> all of the examples I've seen show an associative container.  In other
> words, is array( 'a' => 'b', 'c' => 'd') distinguishable from 
> array( 'c' => 'd', 'a' => 'b').  If not, it is an associative container
> and not a "ordered map" as it says.   If it is an ordered map, what
> is the syntax to get the nth key?

I haven't looked at this specifically in a while, but from memory
it's ordered because they keys stay in the order you define them.
If you print_r the array or use the iteration functions, the keys
come out in their original order.  There are several functions to
sort the array in various ways, and then the new order persists.  

In contrast, Python dictionaries do not preserve the order at all.  If
you print a dictionary or do dic.keys(), they come out in a random
order.  Sometimes this is frustrating because it means you have to keep
a separate list around to show which order you want the elements
processed in.  Of course, there's no concept of sorting a dictionary
in Python.  You'd have to get the keys as a list and sort that.

I assume your two arrays would compare equal.  As for getting the
nth value, $arr[5] gets the item with numeric subscript 5.  If
you mean the absolute fifth element, you could run the next()
iterator function five times or... I don't know.  What does 
foreach do?  A C-like for loop would get only the numeric
subscripts.

-- 
-Mike (Iron) Orr, ir...@ms...  (if mail problems: ms...@oz...)
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