php str_replace function issue - php

Question

I am trying to have this ORIGINAL string converted to the RESULT below using php.
ORIGINAL: "The quick <font color="brown">brown</font> fox jumps over the lazy dog"
RESULT:"god yzal eht revo spmuj xof <font color="brown">nworb</font> kciuq ehT"
What I have done so far is explained like below.
First, strip the HTML tag from the ORIGINAL.
$originalStr = "The quick <font color='brown'>brown</font> fox jumps over the lazy dog";
$stripTags = strip_tags($originalStr);
This results to The quick brown fox jumps over the lazy dog ,
Second, I reverse the result and the word "brown" by using strrev function
$reverseStr = strrev($stripTags);
$brown = strrev("brown");
This results to god yzal eht revo spmuj xof nworb kciuq ehT
Third, I am trying to use str_replace function to find $brown from the reverseStr, and replace it with $openFont $brown $closeFont like below.
$openFont = "<font color='brown'>";
$closeFont = "</font>";
$result = str_replace($brown, $openFont.$brown.$closeFont, $reverseStr);
echo "result -->" . $result . "<br/><br/><br/>";
This results to god yzal eht revo spmuj xof kciuq ehT, NOT the same as the RESULT.
It seems like special characters in font () tag is the problem that may be blocking str_replace to replace the String.
$result = str_replace($brown, "TEST", $reverseStr);
echo "result -->" . $result . "<br/><br/><br/>";
This results to god yzal eht revo spmuj xof TEST kciuq ehT
Does anyone know str_replace is not accepting special characters? and know how I should solve this problem?
If there is another way to solve the problem, I will also be appreciated to hear your suggestion.
(* This is one of the practical questions that I am trying to solve in an algorithm test websites)
UPDATED: I feel so dumb to think that where font tag was. Since tag is meant to change the font color, it was working perfectly in the beginning. Thank you very much everyone for your time!

Answer 1

If it was me, I'd do this (fully tested):
// Original string
$str = 'The quick <font color="brown">brown</font> fox jumps over the lazy dog';
// Strip the font tag
$str = strip_tags( $str );
// Convert string to array
$arr = str_split( $str );
// Reverse the array
$rra = array_reverse( $arr );
// Convert array back to string
$str = implode( $rra );
// Add font tag back in
$str = str_replace('nworb', '<font color="brown">nworb</font>', $str);
// Result
echo $str;

Answer 2

Parse the HTML with something that will give you a DOM API to it.
Write a function that loops over the child nodes of an element.
If a node is a text node, get the data as a string, split it on words, reverse each one, then assign it back.
If a node is an element, recurse into your function.

Answer 3

Use preg_match_all() function.
$originalStr = "The quick <font color='brown'>brown</font> fox jumps over the lazy dog";
preg_match_all('|<[^>]+>(.*)</[^>]+>|U', $originalStr, $matches, PREG_SET_ORDER, 0);
$_tag = $matches[0][0];
$_txt = $matches[0][1];
$newString = str_replace($_tag,$_txt,$originalStr);