I was trying out and learning about bits when i made one of the function worked as expected. The function i just made is a clone of decbin(); but it is not as good as the native one. Just a simple idea of how decbin works.
For numbers, you need to specify the (int) type before using because the result might be different if you leave it out. Great value of float specified will result in an overflow so the max number is returned(0xFFFFFFFF).
The Return is a string with binary in it. I have managed to fix the 32th resource bit loss by reading up on other codes written by others' notes on php.net
<?php
function mydecbin($a = 0){
if(is_int($a)){$a = (float)$a;}
$a = (float)((float)$a>=0?(float)$a:(float)$a*-1);
if($a >= 0xFFFFFFFF){return (string)"11111111111111111111111111111111";}
$buff =array();
$res = ($a & 0x7FFFFFFF) >> 32;
if(0x80000000 & $a){ $res |= (1<<(31-32)); }
$a = floor($a / 2);
while(ceil($a / 2) > 0){
if(ceil($a%2) > -1){$buff[] = ceil($a%2);}
$a = floor($a / 2);}
$buff = array_reverse($buff); $r = '';
foreach($buff as $b){$r .= $b;}
$r .= floor(($res>0?$res:$res*-1)%2);
return (string)$r;
}
// Usage:
$n = (int)281474976711000;
echo "\n\n";
var_dump(mydecbin($n)); // var dump the returned value
echo ' vs '."\n";
var_dump(decbin($n)); // do a check
echo "\n";
var_dump(mydecbin($n) === decbin($n)); // value and type check
/*
Outputs:
string(9) "101011000"
vs
string(9) "101011000"
bool(true)
*/
?>
Cheers
Sam Yong
decbin
(PHP 4, PHP 5)
decbin — 10 進数を 2 進数に変換する
説明
string decbin
( int $number
)
引数 number を 2 進数表現した文字列を返します。 変換することが出来る最大の数は 10 進数の 4294967295 であり、1 が 32 ビット並んだ 2 進数となります。
パラメータ
- number
-
変換したい 10 進数値。
返り値
binary_string を 2 進文字列で表した値を返します。
例
例1 decbin() の例
<?php
echo decbin(12) . "\n";
echo decbin(26);
?>
上の例の出力は以下となります。
1100 11010
decbin
Sam Yong - hellclanner [at] live dot com
06-Sep-2007 07:07
06-Sep-2007 07:07
darkshad3 at yahoo dot com
16-Feb-2007 08:15
16-Feb-2007 08:15
<?php
Print bindecValues("1023");
function bindecValues($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(", ", $stock);
}
?>
The printed result is : 1, 2, 4, 8, 16, 32, 64, 128, 256, 512
heavyraptor
28-Jul-2006 12:18
28-Jul-2006 12:18
I wrote the decoder for the output of Xavier Daull's function "BinString2BinSequence".
<?php
function bs2string($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 $str;
}
?>
Have fun
Xavier Daull
04-Feb-2006 07:57
04-Feb-2006 07:57
A fast function to convert a binary string to a bit sequence
<?php
function BinString2BitSequence($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 11:29
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)) . $bin;
This will convert 11010 to 00011010.
j dot preece at gmail dot com
03-Jan-2006 10:00
03-Jan-2006 10:00
It occured to me there must be a simple way to produce binary numbers from decimal ones with any number of bits, here's my attempt at a decimal to extended binary function. I hope the comments make it clear:
<?php
function decextbin($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($i,4).'<br />';
}
?>
Output:
0000
0001
0010
0011
0100
0101
0110
0111
1000
No need for padding or anything - also goes way over 32 bits. Huzzah. I suspect its limited by the maximum string length in php. Hmmm - Not sure what that is.
dcramer at gmail dot com
27-Apr-2005 08:57
27-Apr-2005 08:57
matt at nexxmedia dot com (06-Dec-2002 04:29) said:
<?php
...
strrev(str_pad(decbin($decval),8,"0",STR_PAD_LEFT));
...
?>
<?php
str_pad(decbin ($decval),8,'0');
?>
produces the same results!
--
That's incorrect, it does not produce the same results.
Stefan
03-Mar-2005 04:35
03-Mar-2005 04:35
matt at nexxmedia dot com (06-Dec-2002 04:29) said:
<?php
...
strrev(str_pad(decbin($decval),8,"0",STR_PAD_LEFT));
...
?>
<?php
str_pad(decbin ($decval),8,'0');
?>
produces the same results!
09-Feb-2005 12:27
base_convert( base_convert('100001000100000000010001001000
0100100000001111111111111111111',2,10),10,2);
return
'1000010001000000000100010010000
100100000010000000000000000000'
this function doesn't work
28-Nov-2004 12:26
<?php // function for converting values >= 2147483648 (2^16)
function decbin4long($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 06:38
15-Oct-2003 06:38
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;
}
matt at nexxmedia dot com
06-Dec-2002 11:29
06-Dec-2002 11:29
A quick one-line bitmask. Great for storing a list of checkbox settings in a MySQL database. This one works for TinyINT (8 bits). Note: I had to make it two lines here so it would fit.
$decval = 83;
/*
decimal to binary, padded with 0s, reversed so the least significant digit is first, split with colons, and then separated into an array
*/
$binstring = strrev(str_pad(decbin ($decval),8,"0",STR_PAD_LEFT))
$bitarray = explode(":",chunk_split($binstring, 1, ":"));
for($x = 0; $x < 8; $x++) {
echo $bitarray[$x]." ";
}
// will output 1 1 0 0 1 0 1 0
php at silisoftware dot com
01-Mar-2002 12:15
01-Mar-2002 12:15
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;
}
gthompsn at ucar dot edu
23-Jan-2002 04:04
23-Jan-2002 04:04
To pad leading zeroes onto the output of decbin, I prefer to use something like this for my 8-bit integer:
$qcStr=sprintf("%08d",decbin($myInt));
--Greg T.
ajl at gmx dot de
09-Oct-2001 05:47
09-Oct-2001 05:47
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>";
?>
oubiwann at yahoo dot com
17-Jan-2001 09:04
17-Jan-2001 09:04
Here's a little binary for counting on your fingers up to 1023 (from 0). It formats/pads the binary number like you wanted.
<pre>
<?php
print "<pre>Dec : Finger Positions\n";
print "---- : ----------------\n";
for ( $i=0; strlen($bin) <=10; ++$i ) {
$bin = decbin($i);
$output = sprintf("%04d : ", $i);
$bin_temp = $bin;
while ( strlen($bin_temp) < 10 ) {
$bin_temp = "0" . $bin_temp;
}
print $output . $bin_temp . "\n";
}
print "</pre>\n";
?>
</pre>
I tried using sprintf("%04d : %10d", $i, $bin) and sprintf("%04d : %10d", $i, $bin + 0), the later an attempt to force the string to act as a number, but neither worked. Maybe it was me...