PHP foreach() with arrays within arrays?

Question

I want to call a function on each element in an array. This is obviously very easy with a foreach(), but where I start breaking down is when arrays contain arrays. Can someone help me out with a function that will execute some code for every key -> value pair from a set of arrays within arrays. The depth could, in theory, be infinite, but a good limit would be 3 iterations (array in array in array) if recursion couldn't work.

An example array would be one taken from $_POST below:

Array
(
    [languages] => Array
    (
        [0] => php
        [1] => mysql
        [2] => inglip
    )

    [rates] => Array
    (
        [incall] => Array
        (
            [1hr] => 10
        )

        [outcall] => Array
        (
            [1hr] => 10
        )

    )
)

Just to make sure, what I want to do is run a piece of code (a function) that is passed every 'end node' in the array structure, so in the example above, it would be called when...

[0] => php
[1] => mysql
[2] => inglip
[1hr] => 10
[1hr] => 10

... is found.

Thanks for any help,

James

Answer 1

Typically, in this kind of situation, you'll have to write a recursive function -- which will deal with an item if it's not an array ; and call itself on an item if it's an array.

Here, you could have something like this :

$arr = array(
    'languages' => array(
        'php', 'mysql', 'inglip', 
    ), 
    'rates' => array(
        'incall' => array('1hr' => 10), 
        'outcall' => array('1hr' => 10), 
    ), 
);

function recurse($item) {
    foreach ($item as $key => $value) {
        if (is_array($value)) {
            recurse($value);
        } else {
            echo "$key : $value\n";
        }
    }
}

And calling this recursive function on your array :

recurse($arr);

Would get you :

0 : php
1 : mysql
2 : inglip
1hr : 10
1hr : 10

Answer 2

I want to call a function on each element in an array. This is obviously very easy with a foreach()

If you want to run a function on every element of a deep array, you can use array_walk_recursive()

array_walk_recursive($array, function($v, $k)
{  
    echo "$k => $v\n";
});

If you want to iterate over each element with foreach, you need a recursive iterator as mentionned previously.

If you're not sure which one to use, go with foreach + recursive iterator. It's easier to grasp for most people.

Answer 3

function traverseArray($array)
{ 
    foreach($array as $key=>$value)
    { 
        if(is_array($value))
        { 
            traverseArray($value); 
        }else{
            echo '['.$key.']'.' => '.$value.'<br />\n'; 
        } 
    }
}