Can someone explain this php function to me?

by

I think it’s great to look over other people’s code (open-source or with permission that is) to better understand the language. While I understand the down-voting, as google would have been a good resource to figure this out, I’ll try to explain it the best I can.

To help explain it, I have rewritten a bit of your code for you.

function xpToNextLevel($level){

        if($level == 0){
            return 200;
        }

        $d = $level / 98;
        $s = 500;
        $m = 65535 * $d; /* 65535 is equivalent to 0xFFFF */
        $k = $m - $s; /* takes (0xFFFF * ($level / 98)) - $s */
        $dk = $k * $d; /* takes ($m - $s) * ($level/98) */
        $unroundedXP = $dk + $s; /* adds (($m-$s) * ($level/98)) to $s */
        $xp = floor($unroundedXP); /* rounds the experience down. */

        return $xp;
}

so, I know in your comment you asked about the level 4. Let’s trace through that!

4 != 0 // thus we continue.
4/98 = 2/49 /*which is roughly ~0.04082, but for the sake of accuracy, I'll leave it as 2/49 */
65535 * (2/49) = ~2674.89795
2674.89795 - 500 = 2174.89795
2174.89795 * 2/49 = ~88.771345
88.771344 + 500 = 588.771344 //This is the unrounded experience
Experience = 588

The floor function basically rounds to the lowest integer. In positive numbers, this means we take the number and toss out everything behind the decimal point. So the number returned is roughly 588. I say roughly because a computer would be more exact about it.

By the way, I believe this is most comparable to a “Arithmetic Series.” More information about that can be found here: http://mathworld.wolfram.com/ArithmeticSeries.html

More Related Contents:

  1. How to get static data member from php object instance? [closed]
  2. Generate all possible 4 digit numbers in PHP and concatenate them with a string [closed]
  3. How to convert the json image url string into Bitmap image to display images in android application
  4. Difference between require, include, require_once and include_once?
  5. PHP function overloading
  6. Get Country of IP Address with PHP [duplicate]
  7. Characters allowed in php array keys?
  8. How to remove a variable from a PHP session array
  9. CURL ERROR: Recv failure: Connection reset by peer – PHP Curl
  10. How to chain method on a newly created object?
  11. PHP decoding and encoding json with unicode characters
  12. SOAP PHP fault parsing WSDL: failed to load external entity?
  13. How to get email address from a long string
  14. PHP PDO vs normal mysql_connect
  15. PHP Warning: Module already loaded in Unknown on line 0
  16. Get numbers from string with PHP
  17. What is the difference between the PHP open tags “
  18. Subtract time in PHP
  19. Pre-incrementation vs. post-incrementation
  20. Simplest way to detect client locale in PHP
  21. php variable inside echo ‘html code’
  22. php count xml elements
  23. Difference between var_dump,var_export & print_r
  24. How to run a cronjob every X minutes?
  25. Using json_encode on objects in PHP (regardless of scope)
  26. Which coding style you use for ternary operator? [closed]
  27. How to remove all numbers from string?
  28. Parsing HTTP_RANGE header in PHP
  29. Installing PDO driver on MySQL Linux server
  30. Undefined index error PHP

Leave a Comment