bindec
(PHP 4, PHP 5)
bindec — Binary to decimal
Описание
Returns the decimal equivalent of the binary number represented by the binary_string argument.
bindec() converts a binary number to an integer or, if needed for size reasons, float.
Список параметров
- binary_string
-
The binary string to convert
Возвращаемые значения
The decimal value of binary_string
Список изменений
| Версия | Описание |
|---|---|
| Since 4.1.0 | The function can now convert numbers that are too large to fit into the platforms integer type, larger values are returned as float in that case. |
Примеры
Пример #1 bindec() example
<?php
echo bindec('110011') . "\n";
echo bindec('000110011') . "\n";
echo bindec('111');
?>
Результат выполнения данного примера:
51 51 7
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Коментарии
## calculate binary with "shift-method" ##
<?php
function dec2bin($decimal_code){
for($half=($decimal_code);$half>=1;$half=(floor($half))/2){
if(($half%2)!=0){
$y.=1;
}
else{
$y.=0;
}
}
$calculated_bin=strrev($y);
return $calculated_bin;
}
?>
## example ##
[bin] 123 = [dec] 1111011
e.g.
123/2 = 61,5 => 1
61/2 = 30,5 => 1
30/2 = 15 => 0
15/2 = 7,5 => 1
7/2 = 3,5 => 1
3/2 = 1,5 => 1
1/2 = 0,5 => 1
(0/2 = 0 finish)
i think a better method than the "shift-method" is my method ^^...
here it comes:
function convert2bin($string) {
$finished=0;
$base=1;
if(preg_match("/[^0-9]/", $string)) {
for($i=0; $string!=chr($i); $i++);
$dec_nr=$i;
}
else $dec_nr=$string;
while($dec_nr>$base) {
$base=$base*2;
if($base>$dec_nr) {
$base=$base/2;
break;
}
}
while(!$finished) {
if(($dec_nr-$base)>0) {
$dec_nr=$dec_nr-$base;
$bin_nr.=1;
$base=$base/2;
}
elseif(($dec_nr-$base)<0) {
$bin_nr.=0;
$base=$base/2;
}
elseif(($dec_nr-$base)==0) {
$bin_nr.=1;
$finished=1;
while($base>1) {
$bin_nr.=0;
$base=$base/2;
}
}
}
return $bin_nr;
}
=====================================================
if you want to reconvert it (from binary to string or integer) you can use this function:
function reconvert($bin_nr) {
$base=1;
$dec_nr=0;
$bin_nr=explode(",", preg_replace("/(.*),/", "$1", str_replace("1", "1,", str_replace("0", "0,", $bin_nr))));
for($i=1; $i<count($bin_nr); $i++) $base=$base*2;
foreach($bin_nr as $key=>$bin_nr_bit) {
if($bin_nr_bit==1) {
$dec_nr+=$base;
$base=$base/2;
}
if($bin_nr_bit==0) $base=$base/2;
}
return(array("string"=>chr($dec_nr), "int"=>$dec_nr));
}
The "smartbindec" function I wrote below will convert any binary string (of a reasonable size) to decimal. It will use two's complement if the leftmost bit is 1, regardless of bit length. If you are getting unexpected negative answers, try zero-padding your strings with sprintf("%032s", $yourBitString).
<?php
function twoscomp($bin) {
$out = "";
$mode = "init";
for($x = strlen($bin)-1; $x >= 0; $x--) {
if ($mode != "init")
$out = ($bin[$x] == "0" ? "1" : "0").$out;
else {
if($bin[$x] == "1") {
$out = "1".$out;
$mode = "invert";
}
else
$out = "0".$out;
}
}
return $out;
}
function smartbindec($bin) {
if($bin[0] == 1)
return -1 * bindec(twoscomp($bin));
else return (int) bindec($bin);
}
?>
A binary to decimal conversion function that takes advantage of the BC library functions to return decimal values of arbitrary length.
Input type must be a string in order to work properly.
<?php
function binary_to_decimal($a) {
$bin_array = str_split($a);
$y=sizeof($bin_array)-1;
for ($x=0; $x<sizeof($bin_array)-1; $x++) {
if ($bin_array[$x] == 1) {
$bin_array[$x] = bcpow(2, $y);
}
$y--;
}
for ($z=0; $z<sizeof($bin_array); $z++) {
$result = bcadd($result, $bin_array[$z]);
}
echo $result;
}
binary_to_decimal('11111');
?>
for converting fractions :
eg : 1001.1101
<?php
function BinaryToDecimal($binary){
$binary=trim($binary);
if (strstr($binary,'.')){
$split=explode('.',$binary);
$integer=$split[0];
$fraction=$split[1];
$digits=str_split($fraction);
$num=sizeof($digits);
for ($i=1; $i<=$num;$i++){
if ($digits[$i-1]>1){
echo '<script>alert("Enter Binary Digits Only {0,1}\n \n eg: 11001 or 11001.011");history.go(-1)</script> ';
}
$exponent=pow(2,-$i);
$fraction_result+=$digits[$i-1]*$exponent;
}
}else{
$integer=$binary;
}
$splits=str_split($integer);
$num=sizeof($splits)-1;
$i=$num;
foreach($splits as $digits){
if ($digits>1){
echo '<script>alert("Enter Binary Digits Only {0,1}\n \n eg: 11001 or 11001.011");history.go(-1)</script> ';
}
$exponent=pow(2,$i);
$integer_result+=$digits*$exponent;
$i--;
}
if($fraction_result){
$result=$integer_result+$fraction_result;
}else {
$result=$integer_result;
}
return $result ;
}
?>
<?php// bindecfunc :)))) I think it works well too :)
function bindecc($str)
{
$str = str_replace(" ", "", $str);
$strr = preg_match('/[^01]/', $str);
if($strr == 1) { return "<b> Error ! only 1 and 0;</b>"; }
$strsig = strlen($str);
$strr1 = strrev($str);
$strf = '';
for($i = $strsig; $i >= 0; $i--)
{
$strf += ($strr1[$i] * pow(2, $i));
#$strf += $str[$i];
}
return $strf;
}
?>
Binary to Decimal conversion using the BCMath extension..
<?php
function BCBin2Dec($Input='') {
$Output='0';
if(preg_match("/^[01]+$/",$Input)) {
for($i=0;$i<strlen($Input);$i++)
$Output=BCAdd(BCMul($Output,'2'),$Input{$i});
}
return($Output);
}
?>
This will simply convert from Base-2 to Base-10 using BCMath (arbitrary precision calculation).
See also: my 'BCDec2Bin' function on the 'decbin' document.
Enjoy,
Nitrogen.
Two functions to convert 16bit or 8bit binary to integer using two's complement. If input exceeds maximum bits, false is returned. Function is easily scalable to x bits by changing the hexadecimals.
<?php function _bin16dec($bin) {
// Function to convert 16bit binary numbers to integers using two's complement
$num = bindec($bin);
if($num > 0xFFFF) { return false; }
if($num >= 0x8000) {
return -(($num ^ 0xFFFF)+1);
} else {
return $num;
}
}
function _bin8dec($bin) {
// Function to convert 8bit binary numbers to integers using two's complement
$num = bindec($bin);
if($num > 0xFF) { return false; }
if($num >= 0x80) {
return -(($num ^ 0xFF)+1);
} else {
return $num;
}
} ?>
Left-shift a string by a number of bytes
<?php
function STR_shl( $szStr,$nBits )
/*-----------------------------*/
{
if ( $nBits < 1 || $nBits > 7 ) /* If not adequate number of bits */
{
return ( $szStr ); /* Return the original string */
} /* if ( $nBits < 1 || $nBits > 7 ) */
if ( ( $iLength = strlen( $szStr ) ) <= 0 ) /* If string empty */
{
return ( $szStr ); /* Return the original string */
} /* if ( ( $iLength = strlen( $szStr ) ) <= 0 ) */
$szRetVal = ''; /* Create an empty string */
$szBits = STR_Binary( $szStr ); /* $szStr in bits */
$szLostBits = STR_Left( $szBits,$nBits ); /* The $nBits leftmost bits of the string */
$szShifted = substr( $szBits,$nBits ) . $szLostBits; /* $szStr left shifted */
for ( $i = 0;$i < $iLength;$i++ ) /* Treat the entire string (per slice of 8 bits) */
{
$szRetVal .= chr( bindec( substr( $szShifted,$i * 8,8 ) ) ); /* Concatenate the CHR to the result string */
} /* for ( $i = 0;$i < $iLength;$i++ ) */
return ( $szRetVal ); /* Return result to caller */
}
?>
Right-shift a string by a number of bytes
<?php
function STR_shr( $szStr,$nBits )
/*-----------------------------*/
{
if ( $nBits < 1 || $nBits > 7 ) /* If not adequate number of bits */
{
return ( $szStr ); /* Return the original string */
} /* if ( $nBits < 1 || $nBits > 7 ) */
if ( ( $iLength = strlen( $szStr ) ) <= 0 ) /* If string empty */
{
return ( $szStr ); /* Return the original string */
} /* if ( ( $iLength = strlen( $szStr ) ) <= 0 ) */
$szRetVal = ''; /* Create an empty string */
$szBits = STR_Binary( $szStr ); /* $szStr in bits */
$szLostBits = STR_Right( $szBits,$nBits ); /* The $nBits rightmost bits of the string */
$szShifted = $szLostBits . substr( $szBits,0,-$nBits ); /* $szStr right shifted */
for ( $i = 0;$i < $iLength;$i++ ) /* Treat the entire string (per slice of 8 bits) */
{
$szRetVal .= chr( bindec( substr( $szShifted,$i * 8,8 ) ) ); /* Concatenate the CHR to the result string */
} /* for ( $i = 0;$i < $iLength;$i++ ) */
return ( $szRetVal ); /* Return result to caller */
}
?>
Additional functions used by the two preceding:
<?php
function STR_Binary( $szStr )
/*-------------------------*/
{
$szRetVal = ''; /* Ready to return an empty string */
if ( ( $iLength = strlen( $szStr ) ) > 0 ) /* If string NOT empty */
{
for ( $i = 0; $i < $iLength;$i++ ) /* Treat each character of the string */
{
$szRetVal .= sprintf( '%08b',ord( $szStr[$i] ) ); /* Turn this char to a binary representation (8 bits) */
} /* for ( $i = 0; $i < $iLength;$i++ ) */
} /* if ( ( $iLength = strlen( $szStr ) ) > 0 ) */
return ( $szRetVal ); /* Return result to caller */
}
function STR_Left( $szStr,$iCount = 1 )
/*----------------------------------*/
{
return substr( $szStr,0,$iCount );
} /* End of function strleft() */
function STR_Right( $szString,$iCount )
/*----------------------------------*/
{
return substr( $szString,0 + strlen( $szString ) - $iCount,$iCount );
}
?>
<?php
//binfloat (For single precision floating point numbers)
//IEE754
//https://en.wikipedia.org/wiki/Single-precision_floating-point_format
function binfloat(Array $num){
$sign = $num[0] ? 1 : -1; //1 bit
$exponent = pow(2,bindec(implode('',array_slice($num,1,8)))-127);
$fraction = array_slice($num,9,count($num)); //23 bits
$fracSum = 1;
for($i=0;$i<23;$i++){
$fracSum += $fraction[$i] * pow(2,-1-$i);
}
return $fracSum*$exponent;
}
$num = isset($_GET['num']) ? $_GET['num'] : '00111110001000000000000000000000';
if(strlen($num)<32){
echo "Invalid binary number $num\n";
exit(1);
}
$num = str_split($num);
echo sprintf('Num is: [%s]%s',implode('',$num),"\n");
echo sprintf('Result is: %s%s',binfloat($num),"\n");