问题
I want to convert numbers in base 36 using PHP. The function base_convert
is not working because I want to convert large numbers: I don't get my initial number if I convert it again from base 36 to decimal.
I tried some function given on multiple websites, but I never get the same result. Also, these two websites (in Javascript) give the same result:
- http://www.unitconversion.org/numbers/base-10-to-base-36-conversion.html
- http://www.translatorscafe.com/cafe/units-converter/numbers/calculator/decimal-to-base-36/
For example 1010701001118000000000000000
has to be converted to 3IZS0ZE1RQ68W8SSW4
.
Here are the functions I tried (and which don't work):
- http://www.php.net/manual/fr/function.base-convert.php#34510
- http://www.php.net/manual/fr/function.base-convert.php#106546
- http://www.tonymarston.net/php-mysql/showsource.php?file=converter.php
- http://www.geoffray.be/blog/php/convertir-des-nombres-en-base-62
回答1:
Here are two simple functions using an algorithm found on Wikipedia, while using bcmath to get the calculations even for very large numbers right:
function fromDecimalToBase($in, $to) {
$in = (string) $in;
$out = '';
for ($i = strlen($in) - 1; $i >= 0; $i--) {
$out = base_convert(bcmod($in, $to), 10, $to) . $out;
$in = bcdiv($in, $to);
}
return preg_replace('/^0+/', '', $out);
}
function fromBaseToDecimal($in, $from) {
$in = (string) $in;
$out = '';
for ($i = 0, $l = strlen($in); $i < $l; $i++) {
$x = base_convert(substr($in, $i, 1), $from, 10);
$out = bcadd(bcmul($out, $from), $x);
}
return preg_replace('/^0+/', '', $out);
}
However, I get 3izs0ze1rq66tifrpc
for the number you've provided - maybe your conversion was wrong there?
回答2:
http://www.pgregg.com/projects/php/base_conversion/base_conversion.php
This page show you how to convert arbitrary length numbers between different bases. I tried your example and it looks like it works in both directions. Source code written in PHP is available.
来源:https://stackoverflow.com/questions/10471991/convertions-between-decimal-and-base-36