str_replace all but first

Question

I have thrown together a little function to find and replace a string within a block of text but it seems to be draining resources. I figure this is because I am trying to run it on a whole HTML page.

All I really want to do is replace all text except the title tag.

Here is my function:

/**
 * Find and replace strings with skip
 *
 * @param string $haystack
 * @param string $needle
 * @param int    $start
 * @param int    $skip
 *
 * @return mixed
 */
function skip_and_replace($haystack, $needle, $start = 0, $skip = 0) {
    $count = 0;
    while ($pos = strpos(($haystack), $needle, $start) !== false) {
        if ($count <= $skip)
            continue;

        substr_replace($haystack, ' M<sup>c</sup>', $pos, strlen($needle));

        $start = $pos+1;

        $count++;
    }

    return $haystack;
}

Can anyone please help with making this function easier on the memory or let me know if there is a better way to achieve my end goal?

Answer 1

If you want to replace all but the first instance of a string, this should work. Can't guarantee it will scale well, but it's the first thing that came to mind.

$haystack = "foo bar baz foo bar baz foo bar baz";
$oldtext = "bar";
$newtext = "rab";

$arr = explode($oldtext, $haystack, 2);
$arr[1] = str_replace($oldtext, $newtext, $arr[1]);
$new_string = implode($oldtext, $arr);