Changes to a PHP Array Not "Sticking" - php

Question

OK so I'm making something to do some data mining but I do changes to an array (by overwritting previous array values) in a loop and they show that they've been changed but once I get outside of a greater loop the values change back to their original values.
Probably easier to give an example:
It starts off like this, turning a bunch of the parts of the array into the word "MATCH".
Now if I was to immediately dump the values of the array it would show that some values have changed to "MATCH" (ie, right after changing the value I would echo the array slot and it would show it's value to be "MATCH") However after I get outside the loop the array changes back to it's original contents
Here is a compressed version of the code:
//i've got this big loop for doing the main work
do {
//Set dat ticker
$q = 0;
// Run through entire previous scrape array to check for matches and mark them as unchanged
do {
if ($itemTitle[$i] == $prodURLS[$q]) {
$prodURLS[$q] = "MATCH";
echo "When the value is printing immediately it shows that it's changed: ".$prodURLS[$q]."<br>";
}
$q++;
} while ($q < $urlArraySize);
$i++;
} while ($i < $itemtitleArraySize);
//If I were to try to print the variable down here it would be reverted to like it was before I changed it to "MATCH"
print_r($prodURLS);

Answer 1

From running your code, setting the variables as follow, it works for me:
$prodURLS = array('a','b','c');
$itemTitle = array('a');
$urlArraySize = count($prodURLS);
$itemtitleArraySize = count($itemTitle);
$i = 0;
My only recommendations with only this amount of information, are:
To provide more context information, as madth3 suggests.
To check the scope in which you are setting/checking values. You may need the & operator to pass variables by reference, or the global keyword to use global variables.
To use the foreach loop, it will make your code smaller and easier to read. Also you won't need to count the size of the arrays and will have other advantages, e.g. in the use of associative arrays. Again, be careful about the use of variables by reference. For example:
foreach ($itemTitle as $item) {
foreach ($prodURLS as &$prod) {
if ($item == $prod) {
$prod = 'MATCH';
}
}
}
unset($prod); //Unset variable set by reference if you are going to use it later on!
Also, you may find useful some of the php array functions like array_walk. Check out the PHP Manual on the array functions reference.
Really, there isn't a lot that can be said from just the code you provided.
Good luck.