cant replace < in php code example

Example: string replace php

#Definition:
str_replace ( array|string $needle , array|string $needle_replacement , string|array $haystack , int &$output_count = null ) : string|array
str_replace ($needle, $needle_replacement, $haystack, $output_count);
  // $needle --> the string value or array of string values you're looking for
  // $needle_replacement --> the string value or array of string values you'll replace the needle(s) with
  // $haysytack --> the string or array of strings you'd like to search/replace needles in
  // $output_count --> not an input, but can be used to get an aggregator to count how many needles were replaced

#Simple Example:
echo str_replace("_", " ", "Hello_World_of_PHP");
  // Prints: "Hello World of PHP"

#Complex Example:  
$vowels = array("a", "e", "i", "o", "u", "A", "E", "I", "O", "U");
/*OR*/ $vowels = ["a", "e", "i", "o", "u", "A", "E", "I", "O", "U"];
echo str_replace($vowels, "", "Hello World of PHP", $count);
  // Prints: "Hll Wrld f PHP"
echo $count
  // Prints: "4"

#This function is case-sensitive. 
  #Use str_ireplace() for case-insensitive replace.