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(PHP 4, PHP 5)
bindec — Umwandlung von binär zu dezimal
Gibt die dezimale Entsprechung der binären Zahl aus dem binary_string-Parameter zurück-
bindec() konvertiert eine binäre Zahl in einen integer oder, falls aus Größengründen benötigt, in einen float.
Der zu konvertierende Binärstring
Der Dezimalwert von binary_string
| Version | Beschreibung |
|---|---|
| Seit 4.1.0 | Die Funktion kann nun Werte, die zu groß für ein integer der jeweiligen Plattform ist, stattdessen als float zurückgeben. |
Beispiel #1 bindec()-Beispiel
<?php
echo bindec('110011') . "\n";
echo bindec('000110011') . "\n";
echo bindec('111');
?>
Das oben gezeigte Beispiel erzeugt folgende Ausgabe:
51 51 7
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 $num;
}
} ?>
Binary to Decimal conversion using the BCMath extension..
<?php
function BCBin2Dec($Input='') {
$Output='0';
if(preg_match("/^[01]+$/",$Input)) {
for($i=0;$i<strlen($Input);$i++)
$Output=BCAdd(BCMul($Output,'2'),$Input{$i});
}
return($Output);
}
?>
This will simply convert from Base-2 to Base-10 using BCMath (arbitrary precision calculation).
See also: my 'BCDec2Bin' function on the 'decbin' document.
Enjoy,
Nitrogen.
<?php
// bindecfunc :)))) I think it works well too :)
function bindecc($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 $strf;
}
?>
for converting fractions :
eg : 1001.1101
<?php
function BinaryToDecimal($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 $result ;
}
?>
A binary to decimal conversion function that takes advantage of the BC library functions to return decimal values of arbitrary length.
Input type must be a string in order to work properly.
<?php
function binary_to_decimal($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');
?>
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($bin);
}
?>
i think a better method than the "shift-method" is my method ^^...
here it comes:
function convert2bin($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));
}
## 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 $calculated_bin;
}
?>
## example ##
[bin] 123 = [dec] 1111011
e.g.
123/2 = 61,5 => 1
61/2 = 30,5 => 1
30/2 = 15 => 0
15/2 = 7,5 => 1
7/2 = 3,5 => 1
3/2 = 1,5 => 1
1/2 = 0,5 => 1
(0/2 = 0 finish)
For converting larger-than-31-bit numbers:
<?php
function Bin2Dec($binstring) {
for ($i=0;$i<strlen($binstring);$i++) {
$decvalue += ((int) substr($binstring, strlen($binstring) - $i - 1, 1)) * pow(2, $i);
}
return $decvalue;
}
?>
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