Advanced Search

Convert a string from one base to another

/ Published in: PHP
Save to your folder(s)

Expand | Embed | Plain Text

Copy this code and paste it in your HTML 
  1. /**
  2.  * Convert a string to a string in another base
  3.  *
  4.  * Note: based on http://php.net/manual/en/function.base-convert.php#55204
  5.  * Note: the bases are only limited to the length of $sFromMap and $sToMap and $sNumber can be any length
  6.  * 
  7.  * @param string $sNumber  the number which to convert
  8.  * @param int $iFromBase  the base from which to convert
  9.  * @param int $iToBase  the base to which to convert
  10.  * @param string $sFromMap  the ascii string to decode the string
  11.  * @param string $sTomMap  the ascii string to encode the string
  12.  * @return string
  13.  */
  14. function baseConvertString($sNumber, $iFromBase, $iToBase = null, 
  15. 	$sFromMap = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_",
  16. 	$sToMap   = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_"
  17. ) {
  18. 	if ($iToBase === null) {
  19. 		// use the max
  20. 		$iToBase = strlen($sToMap);
  21. 	}
  22. 	$sNumber = (string) $sNumber;
  23. 	$length = strlen($sNumber);
  24. 	$result = '';
  25. 	for ($i = 0; $i < $length; $i++) {
  26. 		$aDigits[$i] = strpos($sFromMap, $sNumber{$i});
  27. 	}
  28. 	do { // Loop until whole number is converted
  29. 		$divide = 0;
  30. 		$newlen = 0;
  31. 		for ($i = 0; $i < $length; $i++) { // Perform division manually (which is why this works with big numbers)
  32. 			$divide = $divide * $iFromBase + $aDigits[$i];
  33. 			if ($divide >= $iToBase) {
  34. 				$aDigits[$newlen++] = (int)($divide / $iToBase);
  35. 				$divide = $divide % $iToBase;
  36. 			}	elseif ($newlen > 0) {
  37. 				$aDigits[$newlen++] = 0;
  38. 			}
  39. 		}
  40. 		$length = $newlen;
  41. 		$result = $sToMap{$divide} . $result; // Divide is basically $sNumber % $iToBase (i.e. the new character)
  42. 	} while ($newlen != 0);
  43. 	return $result;	
  44. }

URL: base-convert

Report this snippet


Comments

RSS Icon Subscribe to comments

You need to login to post a comment.