Posted by Jerry Stuckle on 01/08/08 13:00

A Bit Narked wrote:
> On Sun, 6 Jan 2008 23:19:45 +0000,
> Toby A Inkster <usenet200712@tobyinkster.co.uk> wrote:
>
>> A Bit Narked wrote:
>>
>>> And yet you can echo true. The output is '1'.
>> No -- you can't echo a boolean in PHP. Why you try, the boolean is
>> implicitly cast to a string.
>>
>> This:
>>
>> echo $bool;
>>
>> is actually executed as if you coded this:
>>
>> echo (string)$bool;
>>
>> If you look up the manual on type casting, you'll find that FALSE is cast
>> to an empty string, and TRUE is cast to a non-empty string.
>>
>> If you cast to an integer instead of a string, then you'll find that FALSE
>> is cast to 0, which seems to be what you want.
>>
>> echo (int)FALSE;
>
> Apologies for imprecise expression :-) PHP provides free
> casting (e.g. to string in echo) so I ignore it.
>
> My real point is that there is no logical relationship between a
> boolean value of TRUE and a string value '1' _except_ where the
> same relationship yields a string value '0' for boolean FALSE.
> I.e., the C precedent.
>
> I'm not fashed by the idea that there's a special boolean type
> whose values are TRUE and FALSE. But logically, the string
> representations of such sui generis values should be 'true' and
> 'false'. There is no logic whatever in string representions of
> '1' and ''. No one has articulated a relationship such that
> '1' and '' makes any sort of sense.
>
> One of the basic principles of good design is predictability.
> 'From one thing know ten thousand things' as the Chinese stated
> it ages ago. So if there's a well-known precedent, we should
> follow it unless we have a powerful reason for not doing ('Ensure
> that everyone after us makes the same mistake we did', as Maurice
> Wilkes put it, to appreciative laughter). And whatever we do
> should be internally consistent. So the calling sequence for
> some new function should be guessable by anyone who knows the
> sequences of similar functions, one value should tell us about
> neighboring values, and so forth.
>
> The PHP developers' choice for the string reps of true and false
> violate this principle all to buggery, which is what got up my
> nostril.
>
> I thought everyone here would immediately see how daft it is, but
> I expect we're circling the drain as a species precisely because
> so many people -even very smart ones- go through life accepting
> without examination that 'whatever is, is right'.
>

Sorry, but it makes perfect sense.

C does not have real boolean values "true" or "false". Rather, it
gimmicks them up by saying anything with a non-zero value is true, and
anything with a zero value is false. One of the problems is that both 1
and 2 are considered true - but in this case true != true (1 != 2).

PHP does have a real boolean "type" with the values "true" and "false".
So true == true all the time.

PHP can also do conversions. Like with C, anything with a non-zero
value is true, and anything with a zero value is false. This includes
an empty string.

And if we kept doing things the same old way, we'd still be rubbing
sticks together to keep the cave warm. Progress always means change.

--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
==================

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