base_convert

(PHP 4, PHP 5, PHP 7, PHP 8)

base_convertConvertir un número entre bases arbitrarias

Descripción

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

Devuelve una cadena que contiene el número dado por number representado en base tobase. La base en la cual es dado number es especificada en frombase. Tanto frombase como tobase tienen que ser valores entre 2 y 36, inclusive. Los dígitos en números con una base mayor que 10 serán representados con las letras a-z, en donde a significa 10, b significa 11 y z significa 35. No importa si las letras son mayúsculas o minúsculas: number se interpretará correctamente.

Advertencia

base_convert() puede perder precisión en números grandes debido a las propiedades relacionadas con el tipo interno "double" o "flotante" usado. Por favor, consulte la sección sobre Números de punto flotante del manual para información más específica y limitaciones.

Parámetros

number

El número a convertir. Cualquier carácter inválido en number será ignorado silenciosamente.

frombase

La base en que se encuentra number

tobase

La base a la cual convertir number

Valores devueltos

number convertido a base tobase

Ejemplos

Ejemplo #1 Ejemplo de base_convert()

<?php
$hexadecimal
= 'a37334';
echo
base_convert($hexadecimal, 16, 2);
?>

El resultado del ejemplo sería:

101000110111001100110100

Ver también

  • intval() - Obtiene el valor entero de una variable
add a note

User Contributed Notes 6 notes

up
94
PHPCoder at niconet2k dot com
13 years ago
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;
}
?>
up
7
ardavies at tiscali dot co dot uk
11 years ago
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
up
10
Anonymous
6 years ago
While not immediately clear from the description above, a negative sign is also "silently ignored".

base_convert("-12", 10, 10) => 12
up
15
lindsay at bitleap dot com
20 years ago
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 );
}

?>
up
2
ohcc at 163 dot com
7 years ago
<?php
$v
= base_convert(3.14, 10, 10);
var_dump($v);
?>

output: string(3) "314"
up
4
cyrilbele at yahoo dot fr
16 years ago
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;
}
?>
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