Question

The problem I am facing is when I use one foreach inside another and the array of the first foreach has more than 1 entries. What I want to do is to exclude all entries of array 1 from array 2. I’ve been on almost all related posts, cannot solve it by myself, I need a little help if possible. Sorry for my bad English.

Example:

$choice —> array with random number of entries each time (for this example 2)

Example:

/var/www/clients/client1/web1/web/images,/var/www/clients/client1/web1/web/tmp

$list —> array of random number of entries each time (for this example 10000)

Example:

/var/www/clients/client1/web1/web/images,/var/www/clients/client1/web1/web/tmp,/var/www/clients/client1/web1/web/includes,/var/www/clients/client1/web1/web/libraries,......

$list has always more entries than $choice

And I have this code here:

foreach ( $choice as $select )
{
    foreach ( $list as $file )
    {
        if ( (strpos( $file, $select )) !== false ) 
        {
            // exclude this
        }
        else
        {
            // include this
        }
    }
}

What the above code will do (unfortunately) is:

Step 1. Will compare $select entry-1 with all $file entries.

Step 2. Will exclude $select entry-1 from all $file entries and will include the $select entry-2.

Step 3. Will compare $select entry-2 with all $file entries.

Step 4. Will exclude $select entry-2 from all $file entries and will include the $select entry-1.

Result:
Nothing excluded.

Any help truly appreciated. I am on this for like a week, all I have tried is putting them inside out I am out of ideas.
Thank you.

Answer 1

I believe you’re trying to remove items that are in $list from $choice. (Or is it the other way around?) Have you tried the array_diff function? This will work if items in both array are equal. For example:

<?php

//Option 1: array_diff
$bigger = array("A", "B", "C", "D", "E", "F");
$smaller = array("A", "B");

$result = array_diff($bigger, $smaller);
print_r($result);

If you need to do additional processing on the removed items, you can try in_array, but this requires item equality (like above). For example:

//Option 2: in_array (only one foreach loop)
foreach ($smaller as $key => $item) {
    if (in_array($item, $bigger)) {
        //do something to "remove" it, for example:
        unset($smaller[$key]);
        unset($bigger[$key]);
        //...
    }
}
print_r($smaller);
print_r($bigger);

Lastly, if the items in both arrays are not guaranteed to be strictly equals, you could use a double foreach. You’ll need to flag items in the inner loop and process them in the outer loop. For example:

//Option 3: double-foreach (items not strictly equals)
$choice = array(
    "/var/www/clients/client1/web1/web/images",
    "/var/www/clients/client1/web1/web/tmp"
);

$list = array(
    "/var/www/clients/client1/web1/web/images",
    "/var/www/clients/client1/web1/web/tmp",
    "/var/www/clients/client1/web1/web/includes",
    "/var/www/clients/client1/web1/web/libraries",
    // more items
);


foreach ($choice as $choice_key => $choice_item) {
    $exists_in_list = FALSE;
    foreach ($list as $list_key => $list_item) {
        if (strpos($list_item, $choice_item) !== FALSE) {
            //$choice_item is string-contained inside $list_item:
            $exists_in_list = TRUE;

            //Do some processing on $list (while "$list_key" is in scope). For example:
            unset($list[$list_key]); //removes the matching items from $list
            //...

            break;
        }
    }
    if ($exists_in_list) {
        //Do post-processing on $choice. For example:
        unset($choice[$choice_key]); //removes the matching items from $choice
        //...
    }
}

echo '$choice is now ';
print_r($choice);

echo '$list is now ';
print_r($list);

The $result is:

//Option 1:
Array //$result == $bigger - $smaller
(
    [2] => C
    [3] => D
    [4] => E
    [5] => F
)

//Option 2:
Array //$smaller - $bigger
(
)
Array //$bigger - $smaller
(
    [2] => C
    [3] => D
    [4] => E
    [5] => F
)

//Option 3:
$choice is now Array
(
)
$list is now Array
(
    [2] => /var/www/clients/client1/web1/web/includes
    [3] => /var/www/clients/client1/web1/web/libraries
)