SunshinePHP 2020

# decbin

(PHP 4, PHP 5, PHP 7)

decbinDecimal to binary

### Descrierea

decbin ( int `\$number` ) : string

Returns a string containing a binary representation of the given `number` argument.

### Parametri

`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)

### Valorile întoarse

Binary string representation of `number`

### Exemple

Example #1 decbin() example

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

Exemplul de mai sus va afișa:

```1100
11010
```

### A se vedea și

• bindec() - Binary to decimal
• decoct() - Decimal to octal
• dechex() - Decimal to hexadecimal
• base_convert() - Convert a number between arbitrary bases
• printf() - Output a formatted string, using %b, %032b or %064b as the format
• sprintf(), using %b, %032b or %064b as the format

### User Contributed Notes 17 notes

20
MarcelG
5 years ago
``` To add leading zeros I prefer the following:<?php// Add leading zeros\$bin = sprintf( "%08d", decbin( 26 )); // "00011010"?> ```
Xavier Daull
13 years ago
``` A fast function to convert a binary string to a bit sequence<?phpfunction 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?> ```
coverup
2 years ago
``` 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>';?>results0000100100001001000010010000100.... (output is echoed 1000 times)Duracion 0.0134768486023 segundos8Duracion 0.00054407119751 segundos00001001Duracion 0.000833988189697 segundos00001001Thus the winner is <?php\$bin = sprintf( "%08d", decbin( \$decimal ));?> ```
rambabusaravanan at gmail dot com
3 years ago
``` 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";?> ```
php at silisoftware dot com
17 years ago
``` 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;} ```
Anonymous
14 years ago
``` 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. ```
noname at example dot com
4 years ago
``` If you want leading zeros use php built-in features instead of custom functions<?phpprintf('%08b',  \$decimal);?>>> printf('%08b', E_NOTICE)>> 00001000 ```
malcolm.murphy
2 years ago
``` 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?> ```
-2
Nitrogen
10 years ago
``` Decimal to Binary conversion using the BCMath extension.<?phpfunction 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. ```
-1
dj.luiting(.a.t.)gmail.com
5 years ago
``` 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;} ```
-3
12 years ago
``` <?phpPrint 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 ```
-2
Anonymous
14 years ago
``` base_convert( base_convert('1000010001000000000100010010000100100000001111111111111111111',2,10),10,2);return'1000010001000000000100010010000100100000010000000000000000000'this function doesn't work ```
-2
ajl at gmx dot de
18 years ago
``` 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>"; ?> ```
-3
mcampa at gmail dot com
6 years ago
``` 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:0111011111111111011111111111111110101010010101010000000000000101 ```
-5
Silas R (15)
6 years ago
``` 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);    ?> ```
-7
avenger at avenger dot ws
11 years ago
``` Careful trying binary-wise tests with integers:# FFFFFFFFcommand: php -r 'print(decbin(4294967295)."\n");'result: 11111111111111111111111111111111# C3E9CAC8command: 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. ```
-8
Kay
11 years ago
``` I think this is the best function. Is almost endlessy (till 2^50 or something)<?phpfunction 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);?> ```