php replace non matches from two arrays

How do you replace all non matches from one array that are not defined within the other array, i have kind of got working but its not exactly right. as i will show you.

the result is, but wrong.

- - £ 8 - - - - - - - -

The required result should be

 £ 8 - - 

this is how my code is

$vals_to_keep = array(8, 'y', '£');

$replace_if_not_found = array('£', 8, '#', 't'); // replace if not in above array

$result = '';

foreach ($replace_if_not_found as $d) {
 foreach ($vals_to_keep as $ok) {
    if(strcmp($d, $ok) == 0开发者_JAVA百科){
    $result .= $d . " ";
    }else 
    $result .= str_replace($d, $ok ,'-') . " ";
    }
}
echo $result;

use in_array http://php.net/manual/en/function.in-array.php

foreach ($replace_if_not_found as $d) {
if (in_array($d, $vals_to_keep)) 
    $result .= $d . " ";
else 
    $result .= str_replace($d, $ok ,'-') . " ";
}

You could loop over all of the items in $replace_if_not_found replacing them with -, or not, as appropriate.

Using closure in PHP 5.3 or above

$result = array_map(function($item) use ($vals_to_keep) {
    return in_array($item, $vals_to_keep, TRUE) ? $item : '-';
}, $replace_if_not_found);
echo implode(' ', $result);

Using a foreach loop

$result = array();
foreach ($replace_if_not_found as $item) {
    if (in_array($item, $vals_to_keep, TRUE)) {
        $result[] = $item;
    } else {
        $result[] = '-';
    }
}
echo implode(' ', $result;