decbin()
(PHP 4, PHP 5, PHP 7)
十进制转换为二进制
说明
decbin(int $number): string
返回一字符串,包含有给定$number参数的二进制表示。所能转换的最大数值为十进制的 4294967295,其结果为 32 个 1 的字符串。
参数
- $number
Decimal value to convert
Range of inputs on 32-bit machines positive$number negative$number return value 0 0 1 1 2 10 ... normal progression ... 2147483646 1111111111111111111111111111110 2147483647 (largest signed integer) 1111111111111111111111111111111 (31 1's) 2147483648 -2147483648 10000000000000000000000000000000 ... normal progression ... 4294967294 -2 11111111111111111111111111111110 4294967295 (largest unsigned integer) -1 11111111111111111111111111111111 (32 1's) Range of inputs on 64-bit machines positive$number negative$number return value 0 0 1 1 2 10 ... normal progression ... 9223372036854775806 111111111111111111111111111111111111111111111111111111111111110 9223372036854775807 (largest signed integer) 111111111111111111111111111111111111111111111111111111111111111 (63 1's) -9223372036854775808 1000000000000000000000000000000000000000000000000000000000000000 ... normal progression ... -2 1111111111111111111111111111111111111111111111111111111111111110 -1 1111111111111111111111111111111111111111111111111111111111111111 (64 1's)
返回值
Binary string representation of$number
范例
Example #1decbin()例子
<?php echo decbin(12) . "\n"; echo decbin(26); ?>
以上例程会输出:
1100 11010
参见
bindec()
二进制转换为十进制decoct()
十进制转换为八进制dechex()
十进制转换为十六进制base_convert()
在任意进制之间转换数字printf()
输出格式化字符串,using%b,%032bor%064bas the formatsprintf()
,using%b,%032bor%064bas the format
To add leading zeros I prefer the following: <?php // Add leading zeros $bin = sprintf( "%08d", decbin( 26 )); // "00011010" ?>
A fast function to convert a binary string to a bit sequence <?php function BinString2BitSequence($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 ?>
Regarding trailing zeros, after test all the option mention here by others, i have performed my own tests regarding efficiency, here are the results: <?php $decimal = 9; $time_start = microtime(true); for ($i=0;$i<1000;$i++){ $bin = printf('%08b', $decimal); } $time_end = microtime(true); $time = $time_end - $time_start; echo "<hr>Duracion $time segundos<br>\n"; echo $bin . '<br>'; $time_start = microtime(true); for ($i=0;$i<1000;$i++){ $bin = sprintf( "%08d", decbin( $decimal )); } $time_end = microtime(true); $time = $time_end - $time_start; echo "<hr>Duracion $time segundos<br>\n"; echo $bin . '<br>'; $time_start = microtime(true); for ($i=0;$i<1000;$i++){ $bin = decbin($decimal); $bin = substr("00000000",0,8 - strlen($bin)) . $bin; } $time_end = microtime(true); $time = $time_end - $time_start; echo "<hr>Duracion $time segundos<br>\n"; echo $bin . '<br>'; ?> results 0000100100001001000010010000100.... (output is echoed 1000 times) Duracion 0.0134768486023 segundos 8 Duracion 0.00054407119751 segundos 00001001 Duracion 0.000833988189697 segundos 00001001 Thus the winner is <?php $bin = sprintf( "%08d", decbin( $decimal )); ?>
Print as binary format with leading zeros into a variable in one simple statement. <?php $binary = sprintf('%08b', $decimal); // $decimal = 5; echo $binary; // $binary = "00000101"; ?>
Another larger-than-31-bit function. Works for very large numbers, but at the expense of perfect bit-precision as the size increases (I noticed rounding errors past 16 or so decimal places) so use with caution, and only when decbin() won't cut it. function Dec2Bin($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; }
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.
If you want leading zeros use php built-in features instead of custom functions <?php printf('%08b', $decimal); ?> >> printf('%08b', E_NOTICE) >> 00001000
The GNU MP library (http://php.net/manual/en/book.gmp.php) provides methods to efficiently convert binary strings of any length to their binary representation (i.e., a `decbin` equivalent for strings). <?php $str = random_bytes(1024); // binary string example $result = gmp_strval(gmp_import($str), 2); // see manual for options such as endianness $zeroPadded = sprintf('%0' . (strlen($str) * 8) . 's', $result); // zero-pad if needed, e.g. with str_pad, or sprintf as shown here $strAgain = gmp_export(gmp_init($result, 2)); // reverse operation similar to bindec ?>
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.
hi folks, i struggled for a day to get a big decimal number converted into binary, on the windows platform. finally with bcmath functions this is what worked for me. function bc_convert2bin($string) { //got it to work with bcmath functions, works for 64 bit on 32 bit windows machine $finished=0; $base=2; $bin_nr=''; if(preg_match("/[^0-9]/", $string)) { for($i=0; $string!=chr($i); $i++) { $dec_nr=$i; } } else { $dec_nr=$string; } //while( $dec_nr>$base ) { while( bccomp($dec_nr,$base) == 1 ) { //$base=$base*2; $base=bcmul($base,'2'); //if($base>$dec_nr) { if( bccomp($base,$dec_nr) == 1 ) { //$base=$base/2; $base=bcdiv($base,'2'); break; } } while(!$finished) { //if(($dec_nr-$base)>0) { if( bccomp( bcsub($dec_nr,$base) , 0) == 1 ) { //$dec_nr=$dec_nr-$base; $dec_nr=bcsub($dec_nr,$base); $bin_nr.=1; //$base=$base/2; $base=bcdiv($base,'2'); //} elseif(($dec_nr-$base)<0) { } elseif( bccomp( bcsub($dec_nr,$base) , 0) == -1 ) { $bin_nr.=0; //$base=$base/2; $base=bcdiv($base,'2'); //} elseif(($dec_nr-$base)==0) { } elseif( bccomp( bcsub($dec_nr,$base) , 0) == 0 ) { $bin_nr.=1; $finished=1; //while($base>1) { while( bccomp($base,1) == 1 ) { $bin_nr.=0; //$base=$base/2; $base=bcdiv($base,'2'); } } } return $bin_nr; }
<?php Print bindecValues("1023"); function bindecValues($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(", ", $stock); } ?> The printed result is : 1, 2, 4, 8, 16, 32, 64, 128, 256, 512
base_convert( base_convert('100001000100000000010001001000 0100100000001111111111111111111',2,10),10,2); return '1000010001000000000100010010000 100100000010000000000000000000' this function doesn't work
HERE you can convert 64bit instead of 32bit with the standard decbin <? function bigdecbin($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>"; ?>
A little useful little function that returns a binary string with leading 0s: function d2b($n) { return str_pad(decbin($n), 16, "0", STR_PAD_LEFT); } // example: echo d2b(E_ALL); echo d2b(E_ALL | E_STRICT); echo d2b(0xAA55); echo d2b(5); Output: 0111011111111111 0111111111111111 1010101001010101 0000000000000101
This is my System: You can convert a decimal number to a number system you want, like the binary system. <?php function Dec2oSys($numberDec, $SysNum) { if($numberDec != 0) { $numberOSys = ""; for (; $numberDec > 0;) { $numberDecBefore = $numberDec; $numberDec = $numberDec / $SysNum; $pos = strpos($numberDec, '.'); if($pos != false) { $numberDec = floor($numberDec); $numberOSys .= $numberDecBefore - floor($numberDec) * $SysNum; $rest = $numberDecBefore - floor($numberDec) * $SysNum; } else { $numberOSys .= "0"; $rest = 0; } print $numberDec."; Rest:".$rest."<br/>"; } } else { $numberOSys = "0"; } return strrev($numberOSys); } print Dec2oSys(100, 2); ?>
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.
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); ?>