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[nycphp-talk] Accessing non-existent array elements ok?

Kristina Anderson ka at kacomputerconsulting.com
Sun Aug 17 18:51:13 EDT 2008


I'm feeling excited about the ternary operator.   Anything that reduces 
the amount of lines of code (and curly brackets) needed to do something 
will improve my working life & productivity immensely.

-- Kristina


> On Sun, Aug 17, 2008 at 6:10 PM, Kristina Anderson
> <ka at kacomputerconsulting.com> wrote:
> > Hi all.  I have a question regarding the below syntax
> >
> > $result = isset($a['c']) ? $a['c'] : NULL;
> >
> >
> > This is testing two conditions, first if $a['c'] is set, and then, 
if $a
> > ['c'] is NULL...correct?
> 
> No.
> 
> The x ? a : b construct is called the "ternary operator". The 
following example:
> 
>   $x ? $a : $b
> 
> could be read "If $x is true, the expression evaluates to $a.
> Otherwise, the expression evaluates to $b.".
> 
> It's basically a shorthand expression for if / else.
> 
> Mike
> 
> > What would $result be if $a['c'] is set but is not NULL?  The same 
as
> > if $a['c'] was not set?  or...?
> >
> > I've seen similar syntax before, in some code Tedd & I were working
> > with a couple of months back...and just want to make sure I fully
> > understand what is actually happening with it.
> >
> > Thanks.
> >
> > -- Kristina
> >
> >> On Sun, Aug 17, 2008 at 4:49 PM, Michael B Allen <ioplex at gmail.com>
> > wrote:
> >> > Is it ok to access non-existent array elements?
> >> >
> >> > Will accessing an array element using a key that does not exist
> > always
> >> > return NULL?
> >>
> >> it depends on how you have warnings configured. you might be 
getting
> >> them in your log, for example... i believe the result of accessing 
a
> >> non-existent array element is undefined.
> >>
> >> if i were you, i'd prob'ly ask if it exists first:
> >>
> >> <?php
> >>
> >> $result = isset($a['c']) ? $a['c'] : NULL;
> >>
> >> /** OR **/
> >>
> >> $result = array_key_exists('c', $a) ? $a['c'] : NULL;
> >>
> >> ?>
> >>
> >> see:
> >>
> >> http://us2.php.net/function.isset
> >> http://us2.php.net/function.array-key-exists
> >>
> >>
> >> justin
> >> --
> >> http://justinhileman.com
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> >>
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> >>
> >>
> >
> >
> > _______________________________________________
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> >
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> >
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> > http://www.nyphp.org/show_participation.php
> >
> 
> 
> 
> -- 
> Michael B Allen
> PHP Active Directory SPNEGO SSO
> http://www.ioplex.com/
> _______________________________________________
> New York PHP Community Talk Mailing List
> http://lists.nyphp.org/mailman/listinfo/talk
> 
> NYPHPCon 2006 Presentations Online
> http://www.nyphpcon.com
> 
> Show Your Participation in New York PHP
> http://www.nyphp.org/show_participation.php
> 
> 





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