On Sat, 2009-10-03 at 11:57 -0400, Tom Worster wrote:
> On 10/3/09 7:21 AM, "clanc...@cybec.com.au" <clanc...@cybec.com.au> wrote:
>
> > However there is one feature of PHP which, to my mind, is really bad design.
> > How many of
> > you can see anything wrong with the following procedure to search a list of
> > names for a
> > particular name?
> >
> > $i = 0; $j = count ($names); while ($i < $j)
> > { if ($names[$i] == $target) { break; }
> > ++$i;
> > }
> >
> > As long as the names are conventional names, this procedure is probably safe
> > to use.
> > However if you allow the names to be general alphanumeric strings, it is not
> > reliable. One
> > of my programs recently broke down in one particular case, and when I
> > eventually isolated
> > the bug I discovered that it was matching '2260' to '226E1'. (The logic of
> > this is: 226E1
> > = 226*10^1 = 2260).
> >
> > I agree that I was well aware of this trap, and that I should not have used
> > a
> > simple
> > comparison, but it seems to me to be a bizarre design decision to assume
> > that
> > anything
> > which can be converted to an integer, using any of the available notations,
> > is
> > in fact an
> > integer, rather than making the default to simply treat it as a string.
>
> this is odd.
>
> i might think it ok for (2260 == '226E1') to be true since php would be
> doing type juggling in a logical left-to-right manner: we start with an
> integer 2260, next is the juggling comparison operator, then a string, so it
> might reasonably try to convert the string to an integer and then compare.
>
> but with ('2260' == '226E1'), where both lhs and rhs are already of the same
> time, it seems elliptical, to say the least, that php should search the
> types to which it can convert the strings looking for one in which they are
> equal.
>
>
>
I don't know what you mean by elliptical, but I'd expect and certainly
hope that PHP wouldn't try to convert both strings to something which
would mean they had the same value. Also, afaik, if the variables types
are exactly the same, PHP won't try to convert either of them for a
comparison
Thanks,
Ash
http://www.ashleysheridan.co.uk
