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decbin

(PHP 4, PHP 5)

decbinDecimal to binary

Описание

string decbin ( int $number )

Returns a string containing a binary representation of the given number argument. The largest number that can be converted is 4294967295 in decimal resulting to a string of 32 1's.

Список параметров

number

Decimal value to convert

Возвращаемые значения

Binary string representation of number

Примеры

Пример #1 decbin() example

<?php
echo decbin(12) . "\n";
echo 
decbin(26);
?>

Результат выполнения данного примера:

1100
11010

Смотрите также


User Contributed Notes
decbin
Nitrogen
21-Jul-2009 05:30
Decimal to Binary conversion using the BCMath extension.

<?php

function BCDec2Bin($Input='') {
 
$Output='';
 if(
preg_match("/^\d+$/",$Input)) {
   while(
$Input!='0') {
    
$Output.=chr(48+($Input{strlen($Input)-1}%2));
    
$Input=BCDiv($Input,'2');
   }
  
$Output=strrev($Output);
 }
 return((
$Output!='')?$Output:'0');
}

?>

This will simply convert from Base-10 to Base-2 using BCMath (arbitrary precision calculation).

See also: my 'BCBin2Dec' function on the 'bindec' document.
Enjoy,
Nitrogen.
Kay
04-Oct-2008 12:04
I think this is the best function. Is almost endlessy (till 2^50 or something)

<?php
function bin($int)
{
   
$i = 0;
   
$binair = "";
    while(
$int >= pow(2,$i))
    {
       
$i++;
    }
   
    if(
$i != 0)
    {
       
$i = $i-1; //max i
   
}

    while(
$i >= 0)
    {
        if(
$int - pow(2,$i) < 0)
        {
           
$binair = "0".$binair;
        }else{
           
$binair = "1".$binair;
           
$int = $int - pow(2,$i);
        }
       
       
$i--;
    }
    return
$binair;
}

$getal = $_GET['getal'];

   
echo
bin($getal);
?>
avenger at avenger dot ws
24-Aug-2008 01:25
Careful trying binary-wise tests with integers:

# FFFFFFFF
command: php -r 'print(decbin(4294967295)."\n");'
result: 11111111111111111111111111111111

# C3E9CAC8
command: php -r 'print(decbin(3286878920)."\n");'
result: 11000011111010011100101011001000

# regardless of specifying "(int)", using bitwise AND:
command: php -r 'print((int)(3286878920 & 4294967295)."\n");'
result: -1008088376 (int)

# now the expected result will happen (guess the performance impact)
command: php -r 'print(bindec(decbin((3286878920 & 4294967295)))."\n");'
result: 3286878920 (float)

additional note: if you "bitwise and" some random bits with a sequence of 1-bit of the same length, the expected result is the same "random bits sequence" unchanged. If you want to keep this in the integer world for faster comparisons, you risk messing your result for the signed integer size limitation. The maximum value you can use for the desired result is (7FFFFFFF -- or integer 2147483647), half of the maximum 'unsigned' integer 32-bit(platform-dependent) value.
darkshad3 at yahoo dot com
15-Feb-2007 11:15
<?php
Print bindecValues("1023");

function
bindecValues($decimal, $reverse=false, $inverse=false) {
/*
1. This function takes a decimal, converts it to binary and returns the
     decimal values of each individual binary value (a 1) in the binary string.
     You can use larger decimal values if you pass them to the function as a string!
2. The second optional parameter reverses the output.
3. The third optional parameter inverses the binary string, eg 101 becomes 010.
-- darkshad3 at yahoo dot com
*/

   
$bin = decbin($decimal);
    if (
$inverse) {
       
$bin = str_replace("0", "x", $bin);
       
$bin = str_replace("1", "0", $bin);
       
$bin = str_replace("x", "1", $bin);
    }
   
$total = strlen($bin);
   
   
$stock = array();
   
    for (
$i = 0; $i < $total; $i++) {
        if (
$bin{$i} != 0) {
           
$bin_2 = str_pad($bin{$i}, $total - $i, 0);
           
array_push($stock, bindec($bin_2));
        }
    }
   
   
$reverse ? rsort($stock):sort($stock);
    return
implode(", ", $stock);
}
?>

The printed result is : 1, 2, 4, 8, 16, 32, 64, 128, 256, 512
heavyraptor
27-Jul-2006 03:18
I wrote the decoder for the output of Xavier Daull's function "BinString2BinSequence".

<?php
function bs2string($bitseq) {
  if (
strlen($bitseq) % 8 != 0) return false;
 
$str = "";
 
$bitseqlen = strlen($bitseq);
  for(
$i = 0; $i < $bitseqlen; $i += 8) {
  
$str .= chr(bindec(substr($bitseq,$i,8)));
  }
  return
$str;
}
?>

Have fun
Xavier Daull
04-Feb-2006 10:57
A fast function to convert a binary string to a bit sequence

<?php

function BinString2BitSequence($mystring) {   
   
$mybitseq = "";
   
$end = strlen($mystring);
    for(
$i = 0 ; $i < $end; $i++){
       
$mybyte = decbin(ord($mystring[$i])); // convert char to bit string
       
$mybitseq .= substr("00000000",0,8 - strlen($mybyte)) . $mybyte; // 8 bit packed
   
}
    return
$mybitseq;
}

echo
BinString2BitSequence("ABCDEF"); // OUTPUT=010000010100001001000011010001000100010101000110

?>
06-Jan-2006 02:29
Just an example:
If you convert 26 to bin you'll get 11010, which is 5 chars long. If you need the full 8-bit value use this:

$bin = decbin(26);
$bin = substr("00000000",0,8 - strlen($bin)) . $bin;

This will convert 11010 to 00011010.
j dot preece at gmail dot com
03-Jan-2006 01:00
It occured to me there must be a simple way to produce binary numbers from decimal ones with any number of bits, here's my attempt at a decimal to extended binary function. I hope the comments make it clear:

<?php

function decextbin($decimalnumber,$bit)
{
   
/* decextbin function
            by James Preece (j.preece@gmail.com)
            http://www.lovingit.co.uk
   
    Please feel free to use this function. If you find
    if useful I would love to hear from you.
    */

    /* Function to return a binary number with as many
    bits as are requested...
   
    This works on the following principal. A binary number
    represents a figure 2,4,8,16 etc. If we work from the
    top down we can determine if a number contains each figure
    as a fraction and then work with what remains.
   
    For example, if we wish to display the number 10 as a 4 bit
    number we first discover the figure of the maximum bit by doubling
    four times:

    1 2 4 8
   
    The maxiumum figure is 8.
   
    Next we work down the figures:
   
    8 goes in to 10 so the first digit is 1 leaving 2
    4 does not go in to 2 so the second digit is 0
    2 goes in to 2 so the third digit is 1
    1 does not go in to 0 so the fourth digit is 0
   
    Output: 1010
   
    Now for the actual code!

    First we find that maximum value represented by the
    leftmost binary digit. For error checking purposes
    we also calulate the maximum number we can display
    using the number of bits requested:        */
   
   
$maxval = 1;
   
$sumval = 1;
    for(
$i=1;$i<$bit;$i++)
    {
       
$maxval = $maxval * 2;
       
$sumval = $sumval + $maxval;
    }
   
   
/* Using our sumval we now check if it is possible
    to display the decimal number our function received: */
       
   
if ($sumval < $decimalnumber) return 'ERROR - Not enough bits to display this figure in binary.';
   
   
/* Then we work down through the figures, to get a
    better idea of how this works remove the commenting
    from the echo lines */
   
   
for($bitvalue=$maxval;$bitvalue>=1;$bitvalue=$bitvalue/2)
    {
           
//echo 'Bit Value: '.$bitvalue.'<br />';
            //echo 'Decimal Number: '.$decimalnumber.'<br />';
       
       
if (($decimalnumber/$bitvalue) >= 1) $thisbit = 1; else $thisbit = 0;
       
           
//echo 'This Bit: '.$thisbit.'<br /><br />';
   
       
if ($thisbit == 1) $decimalnumber = $decimalnumber - $bitvalue;
   
   
$binarynumber .= $thisbit;
    }

   
/* Finally we return the output... */

return $binarynumber;
}

?>

An example usage might be like so:

<?php

for ($i = 0;$i<=8;$i++)
{
    echo
decextbin($i,4).'<br />';
}

?>

Output:

0000
0001
0010
0011
0100
0101
0110
0111
1000

No need for padding or anything - also goes way over 32 bits. Huzzah. I suspect its limited by the maximum string length in php. Hmmm - Not sure what that is.
Stefan
03-Mar-2005 07:35
matt at nexxmedia dot com (06-Dec-2002 04:29) said:
<?php
...
strrev(str_pad(decbin($decval),8,"0",STR_PAD_LEFT));
...
?>

<?php
str_pad
(decbin ($decval),8,'0');
?>

produces the same results!
08-Feb-2005 03:27
base_convert( base_convert('100001000100000000010001001000
0100100000001111111111111111111',2,10),10,2);

return
'1000010001000000000100010010000
100100000010000000000000000000'

this function doesn't work
27-Nov-2004 03:26
<?php // function for converting values >= 2147483648 (2^16)
 
function decbin4long($long) {
    return
base_convert($long,10,2);
  }
// idea from http://phpclub.ru/talk/showthread.php?postid=407488
?>
gene_wood at example dot com
15-Oct-2003 09:38
This is just an extension off of the first comment. This is a pair of function to convert from an array of binary values to an integer and vice versa. It has a touch of error checking.

/**
* Will convert an array of binary values into an integer for storage
*
* @param        array       $data_array     Array of 31 or less binary values
* @return       integer                     Encoded integer
*/
function array_to_binary_int($data_array) {
    if (count($data_array) > 31) return FALSE;
    foreach ($data_array as $key => $value) {
        if ($value) $data_array[$key] = 1;
        if (!$value) $data_array[$key] = 0;
    }
    $binstring = strrev(implode('', $data_array));
    $bit_integer = bindec($binstring);
    return $bit_integer;
}

/**
* Will convert a stored integer into an array of binary values
*
* @param        integer       $data_integer     Encoded integer
* @return       integer                         Array of binary values
*/
function binary_int_to_array($data_integer) {
    if (($data_integer > 2147483647) OR ($data_integer < 0)) return FALSE;
    $binstring = strrev(str_pad(decbin ($data_integer),31,"0",STR_PAD_LEFT));
    $bitarray = explode(":",chunk_split($binstring, 1, ":"));
    return $bitarray;
}
php at silisoftware dot com
01-Mar-2002 03:15
Another larger-than-31-bit function.
Works for very large numbers, but at the expense of perfect bit-precision as the size increases (I noticed rounding errors past 16 or so decimal places) so use with caution, and only when decbin() won't cut it.

function Dec2Bin($number) {
    while ($number >= 256) {
        $bytes[] = (($number / 256) - (floor($number / 256))) * 256;
        $number = floor($number / 256);
    }
    $bytes[] = $number;
    for ($i=0;$i<count($bytes);$i++) {
        $binstring = (($i == count($bytes) - 1) ? decbin($bytes[$i]) : str_pad(decbin($bytes[$i]), 8, "0", STR_PAD_LEFT)).$binstring;
    }
    return $binstring;
}
ajl at gmx dot de
08-Oct-2001 08:47
HERE you can convert 64bit instead of 32bit with the standard decbin
<?
function bigdecbin($dec,$doublewords=1) {
   
$erg = "";
    do {
         
$rest = $dec%2147483648;
          if (
$rest<0) $rest+=2147483648;
         
$erg = str_pad(decbin($rest),31,"0",STR_PAD_LEFT).$erg;
         
$dec = ($dec-$rest)/2147483648;
      } while ((
$dec>0)&&(!($dec<1)));
     
      return
str_pad($erg,$doublewords*31,"0",STR_PAD_LEFT);
}

echo
"<pre>";
for (
$i=1.5*2147483647.0-10;$i<1.5*2147483647.0+10;$i++) {
    echo
"DEC:".$i." BIN:".bigdecbin($i,2)."<br>";
}
echo
"</pre>";
?>
 

 
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