bindec

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;    }} ?>

## 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)); }

Binary to Decimal conversion using the BCMath extension..<?phpfunction 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.

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", $yourBitString).<?phpfunction twoscomp($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);}?>