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Re: A little tip [message #177449 is a reply to message #177447]

Fri, 30 March 2012 20:19

Jerry Stuckle
Messages: 2598
Registered: September 2010

Karma:

Senior Member

On 3/30/2012 2:18 PM, Shelly wrote:
> On 3/30/2012 1:20 PM, Jerry Stuckle wrote:
>> On 3/30/2012 1:02 PM, Shelly wrote:
>>> Here is something I jist came across, so I am passing it on:
>>> ==========
>>> $val= TRUE;
>>> $val &= TRUE;
>>> print ($val === TRUE) ? "Triple is true\n" : "Triple is false\n";
>>> print ($val == TRUE) ? "Double is true\n" : "Double is false\n";
>>>
>>> Results in:
>>> Triple is false
>>> Double is true
>>> ==========
>>>
>>> Who designed that? It is totally counter-intuitive.
>>>
>>
>> Yes, just another problem with PHP. After the second assignment, $val is
>> actually a reference to TRUE. However, a variable should not be able to
>> reference a constant. For instance, what would the following do?
>>
>> $val &= TRUE;
>> $val = 3;
>>
>> Are we setting TRUE to 3 (that's what a reference should do, after all).
>>
>> This is why other languages don't allow references to constants.
>
> Huh? How is it a reference? I wrote
>
> $val = TRUE;
>
> That sets TRUE as the value contained in the location specified by the
> variable $val.
>
> Then I wrote
>
> $val &= TRUE;
>
> which is identical to
>
> $val = $val && TRUE;
>
> isn't it, which should put into the location of $val the resulting value
> of the logical operation of TRUE AND TRUE -- which SHOULD be TRUE.
> Instead, it is something other than FALSE or ZERO, but not === to TRUE.
>
> Your answer seems to be as if I had written
>
> $val = &TRUE;
> $val = 3;
>
> Am I missing something here?
>

You're right, Shelly - it's AND instead of reference. I was mixing it
up with $val = &TRUE.

But this is a bitwise AND - which means the TRUE will be converted to an
integer 1 and the result will be an integer 1. It is non-zero, so it is
TRUE, but it is not a logical TRUE.

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

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[Message index]

		A little tip By: Shelly[1] on Fri, 30 March 2012 17:02
		Re: A little tip By: Jerry Stuckle on Fri, 30 March 2012 17:20
		Re: A little tip By: Shelly[1] on Fri, 30 March 2012 18:18
		Re: A little tip By: Jerry Stuckle on Fri, 30 March 2012 20:19
		Re: A little tip By: Thomas Mlynarczyk on Fri, 30 March 2012 20:30
		Re: A little tip By: Doug Miller on Fri, 30 March 2012 20:55
		Re: A little tip By: Shelly[1] on Fri, 30 March 2012 20:55
		Re: A little tip By: Jerry Stuckle on Fri, 30 March 2012 21:07
		Re: A little tip By: Jerry Stuckle on Sat, 31 March 2012 14:05
		Re: A little tip By: Shelly[1] on Sat, 31 March 2012 15:27
		Re: A little tip By: Thomas 'PointedEars' on Tue, 03 April 2012 13:52
		Re: A little tip By: Shelly[1] on Tue, 03 April 2012 14:20
		Re: A little tip By: Doug Miller on Fri, 30 March 2012 19:36
		Re: A little tip By: Jerry Stuckle on Fri, 30 March 2012 20:21
		Re: A little tip By: Doug Miller on Fri, 30 March 2012 20:52
		Re: A little tip By: Jerry Stuckle on Fri, 30 March 2012 21:08
		Re: A little tip By: Shelly[1] on Fri, 30 March 2012 21:22
		Re: A little tip By: Mr. B-o-B on Fri, 30 March 2012 23:00
		Re: A little tip By: Scott Johnson on Sat, 31 March 2012 03:33
		Re: A little tip By: Shelly[1] on Fri, 30 March 2012 21:20
		Re: A little tip By: Thomas 'PointedEars' on Tue, 03 April 2012 13:56
		Re: A little tip By: Shelly[1] on Tue, 03 April 2012 14:20
		Re: A little tip By: Michael Fesser on Sat, 31 March 2012 03:04
		Re: A little tip By: Jerry Stuckle on Sat, 31 March 2012 03:31
		Re: A little tip By: Scott Johnson on Sat, 31 March 2012 03:35
		Re: A little tip By: Jerry Stuckle on Sat, 31 March 2012 03:53
		Re: A little tip By: Doug Miller on Sat, 31 March 2012 11:58
		Re: A little tip By: Jerry Stuckle on Sat, 31 March 2012 13:05
		Re: A little tip By: alvaro.NOSPAMTHANX on Mon, 02 April 2012 07:42
		Re: A little tip By: M. Strobel on Mon, 02 April 2012 08:22
		Re: A little tip By: Shelly[1] on Mon, 02 April 2012 12:15
		Re: A little tip By: M. Strobel on Mon, 02 April 2012 12:27
		Re: A little tip By: Shelly[1] on Mon, 02 April 2012 13:40
		Re: A little tip By: M. Strobel on Mon, 02 April 2012 21:43

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