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    bindec

    (PHP 4, PHP 5, PHP 7, PHP 8)

    bindec — Da binario a decimale

    Descrizione

    bindec(string $stringa_binaria): int

    Restituisce il decimale equivalente al numero binario rappresentato dall'argomento stringa_binaria.

    bindec() converte un binario in integer. Il più grande numero che può essere convertito è 31 volte la cifra 1 oppure 2147483647 espresso in formato decimale.

    Example #1 Esempio di bindec()

    <?php
    echo bindec('110011') . "\n";
    echo     bindec('000110011') . "\n";

    echo     bindec('111');
    ?>

    L'esempio precedente visualizzerà: 

     
51 
51 
7

    Vedere anche decbin(), octdec(), hexdec() e base_convert().

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    ＋add a note

    User Contributed Notes 10 notes

    up
    7
    info at rickdg dot nl
    14 years ago
    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;
    }
    }     ?>
    up
    3
    martin at punix dot de
    21 years ago
    ## 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)
    up
    3
    gwbdome at freenet dot de
    20 years ago
    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));
    }
    up
    2
    Nitrogen
    15 years ago
    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.
    up
    1
    alan hogan dot com slash contact
    17 years ago
    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);
    }
    ?>
    up
    0
    patrick dot boens at latosensu dot be
    12 years ago
    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 );
    }
    ?>
    up
    -1
    mashematician at gmail dot com
    16 years ago
    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');

    ?>
    up
    -1
    jpfstange at gmail dot com
    9 years ago
    <?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");
    up
    -1
    flashpack at gmail dot com
    16 years ago
    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     $result ;
    }
    ?>
    up
    -3
    nodarinodo at mail dot ru
    15 years ago
    <?php
    // bindecfunc :)))) I think it works well too :)
    function bindecc($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;
    }
    ?>
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