[RESOLVED] php certification study guide - array_walk_recursive

ronjon

hi guys...

so im reading this book to prep for the php test... and i come across this... (now i do warn you that im a newbie...and this maybe totally elementary.. .but... i need to know and i tried looking it up...but cant find answers)

Passive Iteration
The array_walk() function and its recursive cousin array_walk_recursive() can be
used to perform an iteration of an array in which a user-defined function is called.
Here’s an example:

function setCase(&$value, &$key)
{
$value = strtoupper($value);
}
$type = array(’internal’, ’custom’);
$output_formats[] = array(’rss’, ’html’, ’xml’);
$output_formats[] = array(’csv’, ’json’);
$map = array_combine($type, $output_formats);
array_walk_recursive($map, ’setCase’);
var_dump($map);

Using the custom setCase() function, a simplewrapper for strtoupper(), we are able to convert each each of the array’s values to uppercase. One thing to note about array_walk_recursive() is that it will not call the user-defined function on anything but scalar values; because of this, the first set of keys, internal and custom, are never passed in.

now... what gets me is this whole.... "because of this, the first set of keys, internal and custom, are never passed in"

as far as i can tell ...from what ive been reading.... the way those two arrays are declared and given values... they are essentially the same...

from what ive been reading... creating arrays with the array construct and the [] operators do the same thing...

why is this book telling me that the first array's values, 'internal' and 'custom' are not scalar (or for that matter...why is it telling me that the first array is different from the second array)... i feel they are just as scalar as the other arrays values (all varchars)... can anybody tell me what im not understanding here?

NogDog

If you read what [man]array_combine/man does, I think it will then become clear to you.

Hint: just run this code to see what is actually created prior to the array_walk():

<?php
$type = array(’internal’, ’custom’);
$output_formats[] = array(’rss’, ’html’, ’xml’);
$output_formats[] = array(’csv’, ’json’);
$map = array_combine($type, $output_formats);
printf("<pre>%s</pre>", print_r($map, 1));
?>

You'll see that in array $map, 'internal' and 'custom' are now array indexes, each indexing an array rather than a scalar value.

bradgrafelman

NogDog wrote:
You'll see that in array $map, 'internal' and 'custom' are now array indexes, each indexing an array rather than a scalar value.

Actually, you'll probably see some notices as well, since the curly quotes should be regular single quotes.

ronjon

youre right... after i read what array_combine does... it did make sense. that name "array_combine" is a little misleading... seems like it should take two arrays and combine it to a longer array. but now i know it makes an array out of two arrays... one array for the keys...and the second array used for values.... which explains why the $type array didnt get passed in... because its values were used as keys...rather than values for the new array $map. gotcha. thank you nogdog. i tried putting your code in my site to output something... didnt do it... i guess my godaddy account doesnt use a version of php with that array_combine function... it says that its an unknown function. sounds kinda funky to me... but.. if it says it doesnt know what function im asking for... what can i say eh.

bradgrafelman

ronjon wrote:
it says that its an unknown function

Sounds like your host is using software that is quickly becoming outdated (PHP4) instead of the latest stable release of PHP (PHP5) that has advanced functionality.