On 10/3/09 12:25 PM, "Ashley Sheridan" <a...@ashleysheridan.co.uk> wrote:

> 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

i once had such hope too.

$ php -r "var_dump('2260' == '226E1');"

elliptical: tending to be ambiguous, cryptic, or obscure: an elliptical
prose that is difficult to translate.

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