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Digg  decbin
Decimal to binary
(PHP 4, PHP 5)
Example 1142. decbin() example<?phpThe above example will output: 1100Related Examples ( Source code ) » decbin Examples ( Source code ) » decbin Examples ( Source code ) » bindec Code Examples / Notes » decbingthompsn
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. gene_wood
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; } sam
or pad the string like: substr("000" . $decbin($i), -3, 3); dcramer
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
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! 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)) . $bin; This will convert 11010 to 00011010. j dot preece
It occured to me there must be a simple way to produce binary numbers from decimal ones with any number of bits, here's my attempt at a decimal to extended binary function. I hope the comments make it clear: <?php function decextbin($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($i,4).'<br />'; } ?> Output: 0000 0001 0010 0011 0100 0101 0110 0111 1000 No need for padding or anything - also goes way over 32 bits. Huzzah. I suspect its limited by the maximum string length in php. Hmmm - Not sure what that is. heavyraptor
I wrote the decoder for the output of Xavier Daull's function "BinString2BinSequence". <?php function bs2string($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 $str; } ?> Have fun sam yong - hellclanner
I was trying out and learning about bits when i made one of the function worked as expected. The function i just made is a clone of decbin(); but it is not as good as the native one. Just a simple idea of how decbin works. For numbers, you need to specify the (int) type before using because the result might be different if you leave it out. Great value of float specified will result in an overflow so the max number is returned(0xFFFFFFFF). The Return is a string with binary in it. I have managed to fix the 32th resource bit loss by reading up on other codes written by others' notes on php.net <?php function mydecbin($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($n)); // value and type check /* Outputs: string(9) "101011000" vs string(9) "101011000" bool(true) */ ?> Cheers Sam Yong sterba
I had the same problem on PHP 3.0.9, so the str_repeat was not an option. This maight help: while (strlen($result)<3) $result="0".$result; oubiwann
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, $bin + 0), the later an attempt to force the string to act as a number, but neither worked. Maybe it was me... ajl
HERE you can convert 64bit instead of 32bit with the standard decbin <? function bigdecbin($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)." "; } echo "</pre>"; ?> nospam dot me
do this to pad the binary: str_pad(decbin($dec),3,"0",STR_PAD_LEFT); output like: 001 010 08-feb-2005 03:27
base_convert( base_convert('100001000100000000010001001000 0100100000001111111111111111111',2,10),10,2); return '1000010001000000000100010010000 100100000010000000000000000000' this function doesn't work php
Another larger-than-31-bit function. Works for very large numbers, but at the expense of perfect bit-precision as the size increases (I noticed rounding errors past 16 or so decimal places) so use with caution, and only when decbin() won't cut it. function Dec2Bin($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; } matt
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 xavier daull
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 $mybitseq; } echo BinString2BitSequence("ABCDEF"); // OUTPUT=010000010100001001000011010001000100010101000110 ?> darkshad3
<?php Print bindecValues("1023"); function bindecValues($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(", ", $stock); } ?> The printed result is : 1, 2, 4, 8, 16, 32, 64, 128, 256, 512 27-nov-2004 03:26
<?php // function for converting values >= 2147483648 (2^16) function decbin4long($long) { return base_convert($long,10,2); } // idea from http://phpclub.ru/talk/showthread.php?postid=407488 ?> |
