When should one use the functions str_pos + substr versus preg_match_all for extracting substrings in PHP?

When extracting substrings in PHP, it is generally recommended to use the functions `strpos` and `substr` when dealing with simple patterns or fixed substrings. These functions are more efficient and faster than using `preg_match_all`, which is better suited for extracting substrings based on complex patterns using regular expressions. If you are dealing with a simple substring extraction task, `strpos` and `substr` will provide a more optimized solution.

// Using strpos and substr to extract a substring
$string = "Hello, World!";
$start = strpos($string, "Hello");
$substring = substr($string, $start, 5);
echo $substring; // Output: Hello