Category: Programming

Here’s a crazy gotcha.  I was playing with references when I realized that I was getting the wrong values.

Here’re the values that I used:
$valuearray = array(‘%CTRL%’, ‘%2%’);

Here’s my original loop:

foreach($valuearray as $val)
(
    $params[] = &$val;
)

 

And here’s what the print_r($params) gave me.

Array
(
    [0] => %2%
    [1] => %2%
)

Do you see the problem yet?

In a nutshell, I was trying to load references of each element in $valuearray into $params.  It wasn’t working too well because I was shoving the reference of $val itself into $params.  Whatever $val last points at is what’s going to show up for all elements in the array.  Interesting!  But ultimately not what I was aiming for.

http://www.php.net/manual/en/control-structures.foreach.php

The above link had part of the solution.  The next step of the debugging process would be this loop (I’ve highlighted the change in cyan):

foreach($valuearray as &$val)
(
    $params[] = $val;
)

And here’s what the print_r($params) gave me.

Array
(
    [0] => %CTRL%
    [1] => %2%
)

That’s correct.  But we’re not out of the woods yet.  If you’re trying to shove this into a mysql query that needs references, it should give you an error that a value was received when it was expecting a reference.

Here’s the final iteration (I’ve highlighted the change in cyan):

foreach($valuearray as &$val)
(
    $params[] = &$val;
)

And now I’ve fulfilled my original goal, load references to an array’s elements into another array.

I was creating a website when I had the bright idea of pre-creating a webpage template and then filling in the values that I needed.  At first I was going to roll my own, and then I realized that there were many PHP templating engines in existence already.  I decided to give Twig a try since it seemed to be well-known.

http://devzone.zend.com/1886/creating-web-page-templates-with-php-and-twig-part-1/

• Twig example.
• Shows the basics.
• Unfortunately, does not demonstrate a straightforward loop.

http://readwrite.com/2010/08/31/twig-templating-engine-quick-s#awesm=~opErZeZWdq7zLX

• It’s almost crap.
• Despite its claims, for a five minute guide, it doesn’t show the basics like how to include the dependencies.  In addition, the code throws an error if you put it in a try-catch block.
• However this sample does show how to create a template with a loop.
• The error disappeared when I replaced display/print with render/echo. I wonder if the error hid itself or did I really fix it.