Are there any best practices or guidelines for determining the start and end positions for extracting a substring using PHP?

When extracting a substring using PHP, it is important to determine the start and end positions accurately to ensure that the desired portion of the string is extracted. One common approach is to use the `substr()` function, which takes the string to extract from, the start position (zero-based index), and optionally the length of the substring to extract. To determine the start and end positions, you can use functions like `strpos()` to find the position of a specific substring within the original string.

// Example of extracting a substring using PHP
$string = "Hello, World!";
$start_pos = strpos($string, ",") + 2; // Start position after the comma
$end_pos = strpos($string, "!"); // End position before the exclamation mark
$substring = substr($string, $start_pos, $end_pos - $start_pos);

echo $substring; // Output: World