Inserting new keys/values in multidimensional arrays

[zendak]

$cats['cpuamd']['basename'] = 'cpuamd';
$cats['cpuamd']['title'] = 'CPU AMD';
$cats['cpuintel']['basename'] = 'cpuintel';
$cats['cpuintel']['title'] = 'CPU Intel';
foreach ($cats as $cat) {
 $cat['table'] = 'zz_art_'.$cat['basename'];
 $cat['det_table'] = 'zz_det_'.$cat['basename'];
}

The foreach loop is supposed to add two new key/value pairs to each element of the array. This seems to be a less cumbersome method than adding them manually, as in

$cats['cpuamd']['table'] = 'zz_art_cpuamd';
$cats['cpuamd']['det_table'] = 'zz_det_cpuamd';
$cats['cpuintel']['table'] = 'zz_art_cpuintel';
$cats['cpuintel']['det_table'] = 'zz_det_cpuintel';

Unfortunately, this does not seem to have any effect.
I've monitored the array contents via

echo '<pre>';
print_r($cats);
echo '</pre>';

but this only yields

Array 
( 
 [cpuamd] => Array 
 ( 
 [basename] => cpuamd 
 [title] => CPU AMD 
 ) 
 [cpuintel] => Array 
 ( 
 [basename] => cpuintel 
 [title] => CPU Intel 
 ) 
) 

The "table" and "det_table" keys plus their values do not show up. What am I missing?

[coopster]

It's your foreach loop. What you are doing there is actually creating a whole new array called $cat that has a completely different memory space than $cats. Adding a

print_r($cats); 
print_r($cat);

right after your other would show you what I'm talking about.

Knowing that, you realize you probably want something like...

$cats[$cat]['table'] = 'zz_art_'.$cats[$cat]['basename']; 
$cats[$cat]['det_table'] = 'zz_det_'.$cats[$cat]['basename'];

...but that is going to throw you a warning because you cannot use arrays or objects as keys. Doing so will result in a warning: Illegal offset type. So how do you get them in there? Use array_keys() [php.net] in your foreach loop to return all the keys of the array first and use them accordingly.

foreach (array_keys($cats) as $cat) { 
 $cats[$cat]['table'] = 'zz_art_'.$cats[$cat]['basename']; 
 $cats[$cat]['det_table'] = 'zz_det_'.$cats[$cat]['basename']; 
}

Multidimensional arrays are fun, no doubt, but print_r is your friend. Helps you quickly troubleshoot what is going on at any given step in your script.

[zendak]

Thanks for the insight, coopster. I hadn't realized that I wasn't actually accessing the keys of the existing array in my original loop.
array_keys is my new friend :)