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Description

string base_convert ( string number, int frombase, int tobase )

Returns a string containing number represented in base tobase. The base in which number is given is specified in frombase. Both frombase and tobase have to be between 2 and 36, inclusive. Digits in numbers with a base higher than 10 will be represented with the letters a-z, with a meaning 10, b meaning 11 and z meaning 35.
Пример 1. base_convert() example

<?php $hexadecimal = 'A37334'; echo base_convert($hexadecimal, 16, 2); ?>
Outputs:
101000110111001100110100

Внимание

base_convert() may lose precision on large numbers due to properties related to the internal "double" or "float" type used. Please see the Floating point numbers section in the manual for more specific information and limitations.

See also: intval().

add a note User Contributed Notes
base_convert

CFK
14-Feb-2007 05:07


Here is the function made by David Leppek who works in both way :



<?php

function big_convert ($number,$to_base) {

    $result = "";

    switch ($to_base) {

    case "2":

        $temp = preg_split('//', $number, -1, PREG_SPLIT_DELIM_CAPTURE);

        $lng = strlen($number);

        for ($i = 1;$i <= $lng;$i++) { $result .= str_pad(base_convert($temp[$i], 16, 2), 4, '0', STR_PAD_LEFT); }

        return $result;

    break;



    case "16":

        $bin = substr(chunk_split (strrev($number), 4,'-'), 0, -1);

        $temp = preg_split('[-]', $bin, -1, PREG_SPLIT_DELIM_CAPTURE);

        for ($i = count($temp)-1;$i >= 0;$i--) { $result = $result . base_convert(strrev($temp[$i]), 2, 16); }

        return strtoupper($result);

    break;

    }

}



$bin = "1011010011110010100100101011011101100101001101001111";

echo $hex = big_convert ($bin,16);

echo big_convert ($hex,2);

?>

Ray Paseur sometimes uses GMail
06-Dec-2006 03:55


function roman_numerals($input_arabic_numeral='') {



    if ($input_arabic_numeral == '') { $input_arabic_numeral = date("Y"); } // DEFAULT OUTPUT: THIS YEAR

    $arabic_numeral            = intval($input_arabic_numeral);

    $arabic_numeral_text    = "$arabic_numeral";

    $arabic_numeral_length    = strlen($arabic_numeral_text);



    if (!ereg('[0-9]', $arabic_numeral_text)) {

return false; }



    if ($arabic_numeral > 4999) {

return false; }



    if ($arabic_numeral < 1) {

return false; }



    if ($arabic_numeral_length > 4) {

return false; }



    $roman_numeral_units    = $roman_numeral_tens        = $roman_numeral_hundreds        = $roman_numeral_thousands        = array();

    $roman_numeral_units[0]    = $roman_numeral_tens[0]    = $roman_numeral_hundreds[0]    = $roman_numeral_thousands[0]    = ''; // NO ZEROS IN ROMAN NUMERALS



    $roman_numeral_units[1]='I';

    $roman_numeral_units[2]='II';

    $roman_numeral_units[3]='III';

    $roman_numeral_units[4]='IV';

    $roman_numeral_units[5]='V';

    $roman_numeral_units[6]='VI';

    $roman_numeral_units[7]='VII';

    $roman_numeral_units[8]='VIII';

    $roman_numeral_units[9]='IX';



    $roman_numeral_tens[1]='X';

    $roman_numeral_tens[2]='XX';

    $roman_numeral_tens[3]='XXX';

    $roman_numeral_tens[4]='XL';

    $roman_numeral_tens[5]='L';

    $roman_numeral_tens[6]='LX';

    $roman_numeral_tens[7]='LXX';

    $roman_numeral_tens[8]='LXXX';

    $roman_numeral_tens[9]='XC';



    $roman_numeral_hundreds[1]='C';

    $roman_numeral_hundreds[2]='CC';

    $roman_numeral_hundreds[3]='CCC';

    $roman_numeral_hundreds[4]='CD';

    $roman_numeral_hundreds[5]='D';

    $roman_numeral_hundreds[6]='DC';

    $roman_numeral_hundreds[7]='DCC';

    $roman_numeral_hundreds[8]='DCCC';

    $roman_numeral_hundreds[9]='CM';



    $roman_numeral_thousands[1]='M';

    $roman_numeral_thousands[2]='MM';

    $roman_numeral_thousands[3]='MMM';

    $roman_numeral_thousands[4]='MMMM';



    if ($arabic_numeral_length == 3) { $arabic_numeral_text = "0" . $arabic_numeral_text; }

    if ($arabic_numeral_length == 2) { $arabic_numeral_text = "00" . $arabic_numeral_text; }

    if ($arabic_numeral_length == 1) { $arabic_numeral_text = "000" . $arabic_numeral_text; }



    $anu = substr($arabic_numeral_text, 3, 1);

    $anx = substr($arabic_numeral_text, 2, 1);

    $anc = substr($arabic_numeral_text, 1, 1);

    $anm = substr($arabic_numeral_text, 0, 1);



    $roman_numeral_text = $roman_numeral_thousands[$anm] . $roman_numeral_hundreds[$anc] . $roman_numeral_tens[$anx] . $roman_numeral_units[$anu];

return ($roman_numeral_text);

}

Kiam
12-Aug-2006 05:07


Refering to the function posted by Michael Renner, I would change the line

  $result = $tostring{$divide} . $result;

in

  $result = $chars{$divide} . $result;

as $divide seems garanted to be less than $tobase.

That also eliminates the need of the variable $tostring.



-- Kiam

Michael Renner
17-May-2006 06:24


Here is an unfucked version of the arbitrary-large-number base_convert examples below:



I modified it so that it works as drop-in replacement for base_convert. Attention, no sanity checking is done for the input numbers, anything larger than 36 won't work..



function unfucked_base_convert ($numstring, $frombase, $tobase) {



   $chars = "0123456789abcdefghijklmnopqrstuvwxyz";

   $tostring = substr($chars, 0, $tobase);



   $length = strlen($numstring);

   $result = '';

   for ($i = 0; $i < $length; $i++) {

       $number[$i] = strpos($chars, $numstring{$i});

   }

   do {

       $divide = 0;

       $newlen = 0;

       for ($i = 0; $i < $length; $i++) {

           $divide = $divide * $frombase + $number[$i];

           if ($divide >= $tobase) {

               $number[$newlen++] = (int)($divide / $tobase);

               $divide = $divide % $tobase;

           } elseif ($newlen > 0) {

               $number[$newlen++] = 0;

           }

       }

       $length = $newlen;

       $result = $tostring{$divide} . $result;

   }

   while ($newlen != 0);

   return $result;

}

CJ Dennis
06-Apr-2006 01:03


Really huge numbers might be truncated at both ends.

eg:

<?php

$binary="11010101001111010001110101000100011110010110110".

"001111000010001010001111001100011010110110010010011010".

"001011010000001001011111110001010101101101011010101010".

"000100011101110010110010100111110001010010111010110011".

"001111111100011001011011001110001111110000101011010010";

print(strtoupper(base_convert($binary, 2, 16)));

?>

will output:

9E8EA23CB63C0000000000000000000000000000000000000000000000000000 (64 hex digits)

when the correct result would be:

6A9E8EA23CB63C228F31AD9268B4097F156D6AA11DCB29F14BACCFF196CE3F0AD2 (66 hex digits)

Notice that as well as the result showing '0's after B63C which you would expect it is also missing the first 6A before 9E.

david dot leppek at paybytouch dot com
17-Nov-2005 07:54


I was working on an application that needed to convert a 16 digit HEX number to BINARY.  base_convert was choking when the binary number exceeded 54 characters.



$hex_value    =