Multi-array with one output - php

Question

Here is my code, which currently does not working properly. How can I make it working? My wish is to make output like one string (of course I know how to "convert" array to string):
words altered, added, and removed to make it
Code:
<?php
header('Content-Type: text/html; charset=utf-8');
$text = explode(" ", strip_tags("words altered added and removed to make it"));
$stack = array();
$words = array("altered", "added", "something");
foreach($words as $keywords){
$check = array_search($keywords, $text);
if($check>(-1)){
$replace = " ".$text[$check].",";
$result = str_replace($text[$check], $replace, $text);
array_push($stack, $result);
}
}
print_r($stack);
?>
Output:
Array
(
[0] => Array
(
[0] => words
[1] => altered,
[2] => added
[3] => and
[4] => removed
[5] => to
[6] => make
[7] => it
)
[1] => Array
(
[0] => words
[1] => altered
[2] => added,
[3] => and
[4] => removed
[5] => to
[6] => make
[7] => it
)
)

Answer 1

Without more explanation it's as simple as this:
$text = strip_tags("words altered added and removed to make it");
$words = array("altered", "added", "something");
$result = $text;
foreach($words as $word) {
$result = str_replace($word, "$word,", $result);
}
Don't explode your source string
Loop the words and replace the word with the word and added comma
Or abandoning the loop approach:
$text = strip_tags("words altered added and removed to make it");
$words = array("altered", "added", "something");
$result = preg_replace('/('.implode('|', $words).')/', '$1,', $text);
Create a pattern by imploding the words on the alternation (OR) operator |
Replace found word with the word $1 and a comma

Answer 2

You can use an iterator
// Array with your stuff.
$array = [];
$iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($array));
foreach($iterator as $value) {
echo $v, " ";
}

Answer 3

Your original approach should work with a few modifications. Loop over the words in the exploded string instead. For each one, if it is in the array of words to modify, add the comma. If not, don't. Then the modified (or not) word goes on the stack.
$text = explode(" ", strip_tags("words altered added and removed to make it"));
$words = array("altered", "added", "something");
foreach ($text as $word) {
$stack[] = in_array($word, $words) ? "$word," : $word;
}