RE: [PHP] Re: UNLESS Statement Equivalent
-Original Message-
From: Maciek Sokolewicz [mailto:tula...@gmail.com] On Behalf Of
Maciek Sokolewicz
Sent: 11 March 2013 22:44
unless ( $a and $b )
=
if ( ! ($a and $b) )
So in simple terms, just stick a ! (or the keyword not) in front of
your
expression, and you'll have exactly what you want:
if( not ( ($current_page == $saved_page) and ($current_ip ==
$saved_ip)
and ($current_dt ($saved_dt + 3600) ) ) {
Whilst this is true as far as it goes, I would suggest applying deMorgan's laws
to simplify slightly to
if ( ($current_page != $saved_page) or ($current_ip != $saved_ip) or
($current_dt = ($saved_dt + 3600) ) )
Also, the keyword versions of the Boolean operators are very low
priority, which is why you need all those extra parentheses -- if
you switch to the symbolic versions, you can leave all the internal
parentheses out to give:
if ($current_page != $saved_page || $current_ip != $saved_ip || $current_dt
= $saved_dt + 3600)
Cheers!
Mike
--
Mike Ford,
Electronic Information Developer, Libraries and Learning Innovation,
Portland PD507, City Campus, Leeds Metropolitan University,
Portland Way, LEEDS, LS1 3HE, United Kingdom
E: m.f...@leedsmet.ac.uk T: +44 113 812 4730
To view the terms under which this email is distributed, please go to
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Re: [PHP] Re: UNLESS Statement Equivalent
2013/3/12 Ford, Mike m.f...@leedsmet.ac.uk
-Original Message-
From: Maciek Sokolewicz [mailto:tula...@gmail.com] On Behalf Of
Maciek Sokolewicz
Sent: 11 March 2013 22:44
unless ( $a and $b )
=
if ( ! ($a and $b) )
So in simple terms, just stick a ! (or the keyword not) in front of
your
expression, and you'll have exactly what you want:
if( not ( ($current_page == $saved_page) and ($current_ip ==
$saved_ip)
and ($current_dt ($saved_dt + 3600) ) ) {
Whilst this is true as far as it goes, I would suggest applying deMorgan's
laws
to simplify slightly to
if ( ($current_page != $saved_page) or ($current_ip != $saved_ip) or
($current_dt = ($saved_dt + 3600) ) )
If it is simpler depends, because
not ($everything $must $be $true)
is sometimes more logical :)
Also, the keyword versions of the Boolean operators are very low
priority, which is why you need all those extra parentheses -- if
you switch to the symbolic versions, you can leave all the internal
parentheses out to give:
if ($current_page != $saved_page || $current_ip != $saved_ip ||
$current_dt = $saved_dt + 3600)
Just to throw that in
if (array($current_page, $current_ip, $current_dt) != array($saved_page,
$saved_ip, $saved_dt + 3600))
This at least includes the information, that you have to sets of values,
that should be equal :)
Cheers!
Mike
--
Mike Ford,
Electronic Information Developer, Libraries and Learning Innovation,
Portland PD507, City Campus, Leeds Metropolitan University,
Portland Way, LEEDS, LS1 3HE, United Kingdom
E: m.f...@leedsmet.ac.uk T: +44 113 812 4730
To view the terms under which this email is distributed, please go to
http://disclaimer.leedsmet.ac.uk/email.htm
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RE: [PHP] Re: UNLESS Statement Equivalent
-Original Message-
From: Ford, Mike [mailto:m.f...@leedsmet.ac.uk]
Sent: 12 March 2013 10:51 AM
To: PHP General
Subject: RE: [PHP] Re: UNLESS Statement Equivalent
unless ( $a and $b )
=
if ( ! ($a and $b) )
So in simple terms, just stick a ! (or the keyword not) in front of
your expression, and you'll have exactly what you want:
if( not ( ($current_page == $saved_page) and ($current_ip ==
$saved_ip)
and ($current_dt ($saved_dt + 3600) ) ) {
Whilst this is true as far as it goes, I would suggest applying deMorgan's
laws to simplify slightly to
if ( ($current_page != $saved_page) or ($current_ip != $saved_ip) or
($current_dt = ($saved_dt + 3600) ) )
Also, the keyword versions of the Boolean operators are very low priority,
which is why you need all those extra parentheses -- if you switch to the
symbolic versions, you can leave all the internal parentheses out to give:
if ($current_page != $saved_page || $current_ip != $saved_ip ||
$current_dt = $saved_dt + 3600)
Cheers!
Mike
--
Mike, I presume you're saying the precedence of the Boolean keyword
operators is lower than the Boolean symbol operators, but if so then
wouldn't there be less need for the parentheses? I prefer using the Boolean
keyword operators for both the readability and because of the lower
precedence. Unless I've been wrong all this while and the keyword precedence
is actually higher?
Cheers
Arno
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RE: [PHP] Re: UNLESS Statement Equivalent
-Original Message-
From: Ford, Mike [mailto:m.f...@leedsmet.ac.uk]
Sent: 12 March 2013 10:51 AM
To: PHP General
Subject: RE: [PHP] Re: UNLESS Statement Equivalent
unless ( $a and $b )
=
if ( ! ($a and $b) )
So in simple terms, just stick a ! (or the keyword not) in front of
your expression, and you'll have exactly what you want:
if( not ( ($current_page == $saved_page) and ($current_ip ==
$saved_ip)
and ($current_dt ($saved_dt + 3600) ) ) {
Whilst this is true as far as it goes, I would suggest applying deMorgan's
laws to simplify slightly to
if ( ($current_page != $saved_page) or ($current_ip != $saved_ip) or
($current_dt = ($saved_dt + 3600) ) )
Also, the keyword versions of the Boolean operators are very low priority,
which is why you need all those extra parentheses -- if you switch to the
symbolic versions, you can leave all the internal parentheses out to give:
if ($current_page != $saved_page || $current_ip != $saved_ip ||
$current_dt = $saved_dt + 3600)
Cheers!
Mike
--
Mike, I presume you're saying the precedence of the Boolean keyword
operators is lower than the Boolean symbol operators, but if so then
wouldn't there be less need for the parentheses? I prefer using the Boolean
keyword operators for both the readability and because of the lower
precedence. Unless I've been wrong all this while and the keyword precedence
is actually higher?
Cheers
Arno
--
I checked the manual, the Boolean symbol operators have a higher precedence
than ternary and assignment, while the Boolean keyword operators have the
lowest precedence. So using Boolean keyword operators should obviate
internal parentheses.
Cheers
Arno
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RE: [PHP] Re: UNLESS Statement Equivalent
-Original Message- From: Arno Kuhl [mailto:a...@dotcontent.net] Sent: 12 March 2013 13:04 Mike, I presume you're saying the precedence of the Boolean keyword operators is lower than the Boolean symbol operators, but if so then wouldn't there be less need for the parentheses? I prefer using the Boolean keyword operators for both the readability and because of the lower precedence. Unless I've been wrong all this while and the keyword precedence is actually higher? You are absolutely right, of course -- I failed to engage brain before typing words! Both sets of Boolean operators have lower priority than the comparison operators, so none of the parentheses are needed in either of those cases -- it's the assigning operators (and ?:) that come between the symbolic and keyword Booleans, so that $a = $b = true$c means something different from $a = $b=true and $c Thanks for picking me up on that one! Cheers! Mike -- Mike Ford, Electronic Information Developer, Libraries and Learning Innovation, Portland PD507, City Campus, Leeds Metropolitan University, Portland Way, LEEDS, LS1 3HE, United Kingdom E: m.f...@leedsmet.ac.uk T: +44 113 812 4730 To view the terms under which this email is distributed, please go to http://disclaimer.leedsmet.ac.uk/email.htm -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
