base_convert
(PHP 4, PHP 5)
base_convert — Convert a number between arbitrary bases
Description
$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.
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.
Parameters
-
number -
The number to convert
-
frombase -
The base
numberis in -
tobase -
The base to convert
numberto
Return Values
number converted to base tobase
Examples
Example #1 base_convert() example
<?php
$hexadecimal = 'A37334';
echo base_convert($hexadecimal, 16, 2);
?>
The above example will output:
101000110111001100110100
- PHP Руководство
- Функции по категориям
- Индекс функций
- Справочник функций
- Математические расширения
- Математические функции
- abs
- acos
- acosh
- asin
- asinh
- atan2
- atan
- atanh
- base_convert
- bindec
- ceil
- cos
- cosh
- decbin
- dechex
- decoct
- deg2rad
- exp
- expm1
- floor
- fmod
- getrandmax
- hexdec
- hypot
- intdiv
- is_finite
- is_infinite
- is_nan
- lcg_value
- log10
- log1p
- log
- max
- min
- mt_getrandmax
- mt_rand
- mt_srand
- octdec
- pi
- pow
- rad2deg
- rand
- round
- sin
- sinh
- sqrt
- srand
- tan
- tanh
Коментарии
I needed a function to invert a hex value, which i used for setting font colors when they were on a colored background, that way i will get a contrasting color.
Im sure there are other reasons to use this, you decide!!
<?php
function InvertColor($hex) {
return sprintf("%06s",base_convert(($hex ^ 0xFFFFFF),10,16));
};
print '<td bgcolor="BB2222"><font color="'.InvertColor(0xBB2222).'">Blah</font></td>';
// Prints 44dddd as the font color, which is it's opposite on the color wheel
?>
<?php
function binarycodedstring2dec($binary) {
$len=strlen($binary);
$rows=($len/4)-1;
if (($len%4)>0) {
$pad=$len+(4-($len%4));
$binary=str_pad($binary,$pad,"0",STR_PAD_LEFT);
$len=strlen($binary);
$rows=($len/4)-1;
}
$x=0;
for ($x=0;$x<=$rows;$x++) {
$s=($x*4);
$bins=$binary[$s].$binary[$s+1].$binary[$s+2].$binary[$s+3];
$num=base_convert($bins,2,10);
if ($num>9) {
die("the string is not a proper binary coded decimal\n");
} else {
$res.=$num;
}
}
return $res;
}
?>
a binary coded decimal is converted by taking groups of four from a decimal string,
for example the binary coded decimal string
1000 = 8
10001000 does not = 136 but 88
so
binarycodedstring2dec(1000) = 8
binarycodedstring2dec(11100000111001)=3839
binarycodedstring2dec(100000111001)=839
i truly have no idea if this function will be useful to anyone, i simply failed a physics midterm because i didn't know this so i wrote this function to make sure i would never forget how to convert binary coded decimals
Here are some functions for converting integers to and from base 256. Converting to base 64 is simple given these.
<?php
function to_base256($number, $from_base = 10) {
$binary_number = base_convert($number, $from_base, 2);
$final_string = "";
$new_length = (ceil(strlen($binary_number)/8)*8);
$binary_number = str_pad($binary_number, $new_length, "0", STR_PAD_LEFT);
for($i=($new_length-8); $i>=0; $i-=8) {
$final_string = chr(base_convert(substr($binary_number, $i, 8), 2, 10)).$final_string;
}
return $final_string;
}
function from_base256($string, $to_base = 10) {
$number = "";
for($i=0; $i<strlen($string); $i++) {
$number .= str_pad(base_convert(ord($string{$i}), 10, 2), 8, "0", STR_PAD_LEFT);
}
return base_convert($number, 2, $to_base);
}
?>
Yes, I know that this would be more efficient if it used mod instead of base_convert, but it needs to work with integers > 32 bits.
If you need to use base_convert with numbers larger then 32 bit, the following gmp implementation of base_convert should work.
<?php
/*use gmp library to convert base. gmp will convert numbers > 32bit*/
function gmp_convert($num, $base_a, $base_b)
{
return gmp_strval ( gmp_init($num, $base_a), $base_b );
}
?>
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.
[EDIT BY danbrown AT php DOT net: This function provides conversion of Arabic numerals (those used by most of the world, the standard 1,2,3,4,...) into Roman numerals (I,II,III,IV,...). The original author failed to provide a description, but due to the usefulness of the function, it is being preserved from deletion, and a simple description added.]
<?php
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 ($roman_numeral_text);
}
?>
If you want to do sharding, at some point you will need to decide which shard to target. Here is a simple function to assign the data to a particular shard based on a key (usually identifier of the row)
Here is a simple function to get the shard based on the key and the number of shards available
<?php
function getShard($key,$nbShards) {
$num = substr(base_convert(sha1($key), 16, 10),4,6);
return $num%$nbShards;
}
?>
If you would like to convert numbers into just the uppercase alphabet base and vice-versa (e.g. the column names in a Microsoft Windows Excel sheet..A-Z, AA-ZZ, AAA-ZZZ, ...), the following functions will do this.
<?php
/**
* Converts an integer into the alphabet base (A-Z).
*
* @param int $n This is the number to convert.
* @return string The converted number.
* @author Theriault
*
*/
function num2alpha($n) {
$r = '';
for ($i = 1; $n >= 0 && $i < 10; $i++) {
$r = chr(0x41 + ($n % pow(26, $i) / pow(26, $i - 1))) . $r;
$n -= pow(26, $i);
}
return $r;
}
/**
* Converts an alphabetic string into an integer.
*
* @param int $n This is the number to convert.
* @return string The converted number.
* @author Theriault
*
*/
function alpha2num($a) {
$r = 0;
$l = strlen($a);
for ($i = 0; $i < $l; $i++) {
$r += pow(26, $i) * (ord($a[$l - $i - 1]) - 0x40);
}
return $r - 1;
}
?>
Microsoft Windows Excel stops at IV (255), but this function can handle much larger. However, English words will start to form after a while and some may be offensive, so be careful.
base convert is limited on standard base invented.
In some case, if you want to invented some translate code (for authorizion code 4 example) , I hope is usefull this example of base_convert-AS from decimal in 65imal base for a speedCode.
Some more specifical: you can transform using a db
$speedCodeDEC = $idAziendaMittente.$idAziendaDestinatario.$idDDT ;
//$speedCodeDEC = 3000;
//
$BASECODE = array();
$BASECODE['items'] = 65;
$BASECODE[1]='1';
$BASECODE[2]='2';
$BASECODE[3]='3';
$BASECODE[4]='4';
....
$BASECODE[10]='a';
$BASECODE[11]='b';
$BASECODE[12]='c';
...
$BASECODE[36]='A';
$BASECODE[37]='B';
$BASECODE[38]='C';
...
$BASECODE[61]='Z';
$BASECODE[62]='/';
$BASECODE[63]='-';
$BASECODE[64]='+';
//
//print_r ($BASECODE);TEST
function creaSpeedCode ( $speedCodeDEC,$partialCode="",$BASECODE){
@$division = $speedCodeDEC/$BASECODE['items'];
@$resultINT = floor($speedCodeDEC/$BASECODE['items']);
@$remnant = $speedCodeDEC%$BASECODE['items'];
$partialCode = $BASECODE[$remnant].$partialCode;
echo "
<br>
Inserito speedCodeDEC:$speedCodeDEC - partialCode:$partialCode<br>
items : ".$BASECODE['items']."<br>
division : $division <br>
resultINT : $resultINT <br>
remnant : $remnant <br>
partialCode : $partialCode <br>
";//TEST
if ($resultINT > 65) $partialCode = creaSpeedCode($resultINT,$partialCode,$BASECODE);
return $BASECODE[$resultINT].$partialCode;
}
echo $speedCodeDEC."<br>";
echo $risultato = creaSpeedCode ( $speedCodeDEC,"",$BASECODE);
A RFC 4648 Compliant Base32 encode. Send me an email if you end up making this thing more efficient with bitwise operations and whatever else.
<?php
/**
* Encode in Base32 based on RFC 4648.
* Requires 20% more space than base64
* Great for case-insensitive filesystems like Windows and URL's (except for = char which can be excluded using the pad option for urls)
*
* @package default
* @author Bryan Ruiz
**/
class Base32 {
private static $map = array(
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', // 7
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', // 15
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', // 23
'Y', 'Z', '2', '3', '4', '5', '6', '7', // 31
'=' // padding char
);
private static $flippedMap = array(
'A'=>'0', 'B'=>'1', 'C'=>'2', 'D'=>'3', 'E'=>'4', 'F'=>'5', 'G'=>'6', 'H'=>'7',
'I'=>'8', 'J'=>'9', 'K'=>'10', 'L'=>'11', 'M'=>'12', 'N'=>'13', 'O'=>'14', 'P'=>'15',
'Q'=>'16', 'R'=>'17', 'S'=>'18', 'T'=>'19', 'U'=>'20', 'V'=>'21', 'W'=>'22', 'X'=>'23',
'Y'=>'24', 'Z'=>'25', '2'=>'26', '3'=>'27', '4'=>'28', '5'=>'29', '6'=>'30', '7'=>'31'
);
/**
* Use padding false when encoding for urls
*
* @return base32 encoded string
* @author Bryan Ruiz
**/
public static function encode($input, $padding = true) {
if(empty($input)) return "";
$input = str_split($input);
$binaryString = "";
for($i = 0; $i < count($input); $i++) {
$binaryString .= str_pad(base_convert(ord($input[$i]), 10, 2), 8, '0', STR_PAD_LEFT);
}
$fiveBitBinaryArray = str_split($binaryString, 5);
$base32 = "";
$i=0;
while($i < count($fiveBitBinaryArray)) {
$base32 .= self::$map[base_convert(str_pad($fiveBitBinaryArray[$i], 5,'0'), 2, 10)];
$i++;
}
if($padding && ($x = strlen($binaryString) % 40) != 0) {
if($x == 8) $base32 .= str_repeat(self::$map[32], 6);
else if($x == 16) $base32 .= str_repeat(self::$map[32], 4);
else if($x == 24) $base32 .= str_repeat(self::$map[32], 3);
else if($x == 32) $base32 .= self::$map[32];
}
return $base32;
}
public static function decode($input) {
if(empty($input)) return;
$paddingCharCount = substr_count($input, self::$map[32]);
$allowedValues = array(6,4,3,1,0);
if(!in_array($paddingCharCount, $allowedValues)) return false;
for($i=0; $i<4; $i++){
if($paddingCharCount == $allowedValues[$i] &&
substr($input, -($allowedValues[$i])) != str_repeat(self::$map[32], $allowedValues[$i])) return false;
}
$input = str_replace('=','', $input);
$input = str_split($input);
$binaryString = "";
for($i=0; $i < count($input); $i = $i+8) {
$x = "";
if(!in_array($input[$i], self::$map)) return false;
for($j=0; $j < 8; $j++) {
$x .= str_pad(base_convert(@self::$flippedMap[@$input[$i + $j]], 10, 2), 5, '0', STR_PAD_LEFT);
}
$eightBits = str_split($x, 8);
for($z = 0; $z < count($eightBits); $z++) {
$binaryString .= ( ($y = chr(base_convert($eightBits[$z], 2, 10))) || ord($y) == 48 ) ? $y:"";
}
}
return $binaryString;
}
}
Short arabic2roman conveter:
<?php
function rome($N){
$c='IVXLCDM';
for($a=5,$b=$s='';$N;$b++,$a^=7)
for($o=$N%$a,$N=$N/$a^0;$o--;$s=$c[$o>2?$b+$N-($N&=-2)+$o=1:$b].$s);
return $s;
}
?>
And it works :)
A simple function to convert an int to any base.
<?php
function intToAlphaBaseN($n,$baseArray) {
$l=count($baseArray);
$s = '';
for ($i = 1; $n >= 0 && $i < 10; $i++) {
$s = $baseArray[($n % pow($l, $i) / pow($l, $i - 1))].$s;
$n -= pow($l, $i);
}
return $s;
}
$alpha=array('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z');
$r=rand(0, 99999999999);
echo(intToAlphaBaseN($r,$alpha));
?>
Convert an arbitrarily large number from any base to any base.
string convBase(string $numberInput, string $fromBaseInput, string $toBaseInput)
$numberInput number to convert as a string
$fromBaseInput base of the number to convert as a string
$toBaseInput base the number should be converted to as a string
examples for $fromBaseInput and $toBaseInput
'0123456789ABCDEF' for Hexadecimal (Base16)
'0123456789' for Decimal (Base10)
'01234567' for Octal (Base8)
'01' for Binary (Base2)
You can really put in whatever you want and the first character is the 0.
Examples:
<?php
convBase('123', '0123456789', '01234567');
//Convert '123' from decimal (base10) to octal (base8).
//result: 173
convBase('70B1D707EAC2EDF4C6389F440C7294B51FFF57BB', '0123456789ABCDEF', '01');
//Convert '70B1D707EAC2EDF4C6389F440C7294B51FFF57BB' from hexadecimal (base16) to binary (base2).
//result:
//111000010110001110101110000011111101010110000101110
//110111110100110001100011100010011111010001000000110
//001110010100101001011010100011111111111110101011110
//111011
convBase('1324523453243154324542341524315432113200203012', '012345', '0123456789ABCDEF');
//Convert '1324523453243154324542341524315432113200203012' from senary (base6) to hexadecimal (base16).
//result: 1F9881BAD10454A8C23A838EF00F50
convBase('355927353784509896715106760','0123456789','Christopher');
//Convert '355927353784509896715106760' from decimal (base10) to undecimal (base11) using "Christopher" as the numbers.
//result: iihtspiphoeCrCeshhorsrrtrh
convBase('1C238Ab97132aAC84B72','0123456789aAbBcCdD', '~!@#$%^&*()');
//Convert'1C238Ab97132aAC84B72' from octodecimal (base18) using '0123456789aAbBcCdD' as the numbers to undecimal (base11) using '~!@#$%^&*()' as the numbers.
//result: !%~!!*&!~^!!&(&!~^@#@@@&
function convBase($numberInput, $fromBaseInput, $toBaseInput)
{
if ($fromBaseInput==$toBaseInput) return $numberInput;
$fromBase = str_split($fromBaseInput,1);
$toBase = str_split($toBaseInput,1);
$number = str_split($numberInput,1);
$fromLen=strlen($fromBaseInput);
$toLen=strlen($toBaseInput);
$numberLen=strlen($numberInput);
$retval='';
if ($toBaseInput == '0123456789')
{
$retval=0;
for ($i = 1;$i <= $numberLen; $i++)
$retval = bcadd($retval, bcmul(array_search($number[$i-1], $fromBase),bcpow($fromLen,$numberLen-$i)));
return $retval;
}
if ($fromBaseInput != '0123456789')
$base10=convBase($numberInput, $fromBaseInput, '0123456789');
else
$base10 = $numberInput;
if ($base10<strlen($toBaseInput))
return $toBase[$base10];
while($base10 != '0')
{
$retval = $toBase[bcmod($base10,$toLen)].$retval;
$base10 = bcdiv($base10,$toLen,0);
}
return $retval;
}
?>
Extending base_convert to bases above 36, up to base 62.
<?php
function base_convert_x( $_number='', $_frBase=10, $_toBase=62 ) {
# Today's Date - C74 - convert a string (+ve integer) from any arbitrary base to any arbitrary base, up to base 62, using 0-9,A-Z,a-z
#
# Usage : echo base_convert_x( 123456789012345, 10, 32 );
$_10to62 = array(
'0' => '0', '1' => '1', '2' => '2', '3' => '3', '4' => '4', '5' => '5', '6' => '6', '7' => '7', '8' => '8', '9' => '9', '00' => '0', '01' => '1', '02' => '2', '03' => '3', '04' => '4', '05' => '5', '06' => '6', '07' => '7',
'10' => 'A', '11' => 'B', '12' => 'C', '13' => 'D', '14' => 'E', '15' => 'F', '16' => 'G', '17' => 'H', '18' => 'I', '19' => 'J', '20' => 'K', '21' => 'L', '22' => 'M', '23' => 'N', '24' => 'O', '25' => 'P', '26' => 'Q', '27' => 'R',
'30' => 'U', '31' => 'V', '32' => 'W', '33' => 'X', '34' => 'Y', '35' => 'Z', '36' => 'a', '37' => 'b', '38' => 'c', '39' => 'd', '40' => 'e', '41' => 'f', '42' => 'g', '43' => 'h', '44' => 'i', '45' => 'j', '46' => 'k', '47' => 'l',
'50' => 'o', '51' => 'p', '52' => 'q', '53' => 'r', '54' => 's', '55' => 't', '56' => 'u', '57' => 'v', '58' => 'w', '59' => 'x', '60' => 'y', '61' => 'z' );
$_62to10 = array(
'0' => '00', '1' => '01', '2' => '02', '3' => '03', '4' => '04', '5' => '05', '6' => '06', '7' => '07', '8' => '08', '9' => '09', 'A' => '10', 'B' => '11', 'C' => '12', 'D' => '13', 'E' => '14', 'F' => '15', 'G' => '16', 'H' => '17',
'K' => '20', 'L' => '21', 'M' => '22', 'N' => '23', 'O' => '24', 'P' => '25', 'Q' => '26', 'R' => '27', 'S' => '28', 'T' => '29', 'U' => '30', 'V' => '31', 'W' => '32', 'X' => '33', 'Y' => '34', 'Z' => '35', 'a' => '36', 'b' => '37',
'e' => '40', 'f' => '41', 'g' => '42', 'h' => '43', 'i' => '44', 'j' => '45', 'k' => '46', 'l' => '47', 'm' => '48', 'n' => '49', 'o' => '50', 'p' => '51', 'q' => '52', 'r' => '53', 's' => '54', 't' => '55', 'u' => '56', 'v' => '57',
'y' => '60', 'z' => '61' );
# ---- First convert from frBase to base-10
$_in_b10 = 0;
$_pwr_of_frB = 1; # power of from base, eg. 1, 8, 64, 512
$_chars = str_split( $_number ); # split input # into chars
$_str_len = strlen( $_number );
$_pos = 0;
while ( $_pos++ < $_str_len ) {
$_char = $_chars[$_str_len - $_pos];
$_in_b10 += (((int) $_62to10[$_char] ) * $_pwr_of_frB);
$_pwr_of_frB *= $_frBase;
}
# ---- Now convert from base-10 to toBase
$_dividend = (int) $_in_b10; # name dividend easier to follow below
$_in_toB = ''; # number string in toBase
while ( $_dividend > 0 ) {
$_quotient = (int) ( $_dividend / $_toBase ); # eg. 789 / 62 = 12 ( C in base 62 )
$_remainder = '' . ( $_dividend % $_toBase ); # 789 % 62 = 45 ( j in base 62 )
$_in_toB = $_10to62[$_remainder] . $_in_toB; # 789 (in base 10) = Cj (in base 62)
$_dividend = $_quotient; # new dividend is the quotient from base division
}
if ( $_in_toB == '' )
$_in_toB = '0';
return $_in_toB; # base $_toBase string
}
# --------- examples -------
echo base_convert_x( '3456789ABCDEF', 16, 10 ) . "\n"; # 920735923817967
echo base_convert( '3456789ABCDEF', 16, 10 ) . "\n"; # 920735923817967
?>
If you use base_convert to convert a large (eg. 80-bit) hexadecimal to base-36, you might observe:
ABCDEF00001234567890 (hexadecimal) => 3O47RE02JZSW0KS8 (base-36) => ABCDEF00001240000000 (hexadecimal)
This is normal and is due to the loss of precision on large numbers.
I have written a string-based function using the built-in BC Math Extension which will overcome this and similar problems.
<?php
function str_baseconvert($str, $frombase=10, $tobase=36) {
$str = trim($str);
if (intval($frombase) != 10) {
$len = strlen($str);
$q = 0;
for ($i=0; $i<$len; $i++) {
$r = base_convert($str[$i], $frombase, 10);
$q = bcadd(bcmul($q, $frombase), $r);
}
}
else $q = $str;
if (intval($tobase) != 10) {
$s = '';
while (bccomp($q, '0', 0) > 0) {
$r = intval(bcmod($q, $tobase));
$s = base_convert($r, 10, $tobase) . $s;
$q = bcdiv($q, $tobase, 0);
}
}
else $s = $q;
return $s;
}
?>
Typical use-cases:
1. Convert a large arbitrary precision number to base-36.
2. Convert a 32-char hexadecimal UUID (128-bit) to a 25-char base-36 unique key, and vice versa.
Examples:
<?php
$b16 = 'ABCDEF00001234567890';
$b36 = str_baseconvert($b16, 16, 36);
echo ("$b16 (hexadecimal) = $b36 (base-36) \\n");
$uuid = 'ABCDEF01234567890123456789ABCDEF';
$ukey = str_baseconvert($uuid, 16, 36);
echo ("$uuid (hexadecimal) = $ukey (base-36) \\n");
?>
ABCDEF00001234567890 (hexadecimal) = 3o47re02jzqisvio (base-36)
ABCDEF01234567890123456789ABCDEF (hexadecimal) = a65xa07491kf5zyfpvbo76g33 (base-36)
Convert any length bits to HEX:
function bits2hex($bin)
{
$out = "";
for($i=0;$i<strlen($bin);$i+=8)
{
$byte = substr($bin,$i,8); if( strlen($byte)<8 ) $byte .= str_repeat('0',8-strlen($byte));
$out .= base_convert($byte,2,16);
}
return $out;
}
VARNING! If the last byte is incomplete, it is supplemented with zeros as string!
Example of using base_convert to generate random passwords
function random_password()
{
$rvalue1 = mt_rand(100,999);
$rvalue2 = time();
$rvalue3 = mt_rand(1000,9999);
$rvalue4 = mt_rand(1,9);
$rvalue5 = mt_rand(101,109);
//combine values
$rvalues = intval(((($rvalue2.$rvalue3) + $rvalue1)*$rvalue4) / $rvalue5);
//return value in base-35 (will contain chars from '0' to 'z')
return base_convert($rvalues,10,35);
}
Change the range of rvalue5 to get more or less characters. This setting
will return 8 chars.
In order to convert base 26 (hexavigesimal) of just alphanumeric characters (A-Z), wthout integers, (as descibed at http://en.wikipedia.org/wiki/Hexavigesimal), I found this to be useful:
function base_convert_alpha( $str, $from, $to )
{
$r = range( 'A', 'Z' );
$clean = str_replace( $r, array_keys($r), $str );
return base_convert( $clean, $from, $to );
}
echo base_convert_alpha( "BAC", 26, 10 );
//$clean = 102 which then returns 678
I wrote this as part of a college assignment to shorten urls. It works for any base and with any range of characters, eg. A-Za-z0-9 etc. Hope it helps someone.
<?php
$base = range(0, 1);
$number = 255;
function translate($base, $number){
$array = array();
$n = count($base);
$i = $number;
while(true){
/* by dividing $i % $n we can get the remainder after the number has
* been divided by the base. Subtracting the result from $i (number), and dividing
* by $n (base) we reassign the result to $i, thus moving on to the next smallest
* exponent, and around for another go of the loop. It continues doing this, churning
* out the remainders until $i <= 0 at which point it breaks.
*/
if($i <= 0){
break;
}else{
$r = ($i % $n);
//reassign the value of $i
$i = ($i - $r) / $n;
$array[] = $base[$r];
}
}
$string = implode("", $array);
return $string;
}
$string = translate($base, $number);
echo $string;
// prints 11111111
?
Note that the method can only convert max 1024 long numbers. Most people don't nee that but once I ran into an issue where binary string was converted into alphanumeric. In such case, you need to split them, convert them and join.<?php
$v = base_convert(3.14, 10, 10);
var_dump($v);
?>
output: string(3) "314"
Base62x gives an alternative way for traditional Base62 and/or Base64.
base62x_encode / base62x_decode would be merged into PHP as an extra module in the future.
Prior to that, users can download the PHP extra module via: https://github.com/wadelau/Base62x
some other mini implementation of base32 without error catching. just bring things from 5 to 8 and 8 to 5 bit. greetings. mho
<?
function base32_decode($d)
{
list($t, $b, $r) = array("ABCDEFGHIJKLMNOPQRSTUVWXYZ234567", "", "");
foreach(str_split($d) as $c)
$b = $b . sprintf("%05b", strpos($t, $c));
foreach(str_split($b, 8) as $c)
$r = $r . chr(bindec($c));
return($r);
}
function base32_encode($d)
{
list($t, $b, $r) = array("ABCDEFGHIJKLMNOPQRSTUVWXYZ234567", "", "");
foreach(str_split($d) as $c)
$b = $b . sprintf("%08b", ord($c));
foreach(str_split($b, 5) as $c)
$r = $r . $t[bindec($c)];
return($r);
}
?>
While not immediately clear from the description above, a negative sign is also "silently ignored".
base_convert("-12", 10, 10) => 12
Convert Large Integer to Hexadecimal without PHP Math extension.
<?php
/*
* Created by Michael Renner 17-May-2006 03:24
*/
function baseConvert($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;
}
Addition to the method suggested by "lindsay at bitleap dot com".
Easy way convert hex string to decimal string for 32-bit version of php
<?php
$test = '0x7000005a00000ea5';
$rrrrr = gmp_strval($test);
var_dump($test, $rrrrr);
?>
will return
//string '0x7000005a00000ea5' (length=18)
//string '8070450918794989221' (length=19)
base_convert will return 8070450918794990488