hexdec

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

hexdec — Wandelt von hexadezimal zu dezimal um

Beschreibung

hexdec(string $hex_string): int|float

Gibt die dezimale Entsprechung der in hexadezimaler Darstellung angegebenen Zahl hex_string zurück. Die Funktion hexdec() wandelt eine hexadezimale Zeichenkette in eine Dezimalzahl um.

hexdec() ignoriert alle nicht hexadezimal kodierten Zeichen (0-9 a-f) in hex_string. Von PHP 7.4.0 an ist die Übergabe jeglicher ungültiger Zeichen missbilligt.

Parameter-Liste

hex_string: Die umzuwandelnde hexadezimale Zeichenkette.

Rückgabewerte

Dezimaldarstellung von hex_string.

Changelog

Version	Beschreibung
7.4.0	Die Übergabe ungültiger Zeichen löst nun einen Deprecation-Hinweis aus. Das Ergebnis wird weiterhin so berechnet, als würden die ungültigen Zeichen nicht existieren.

Beispiele

Beispiel #1 hexdec()-Beispiel

<?php
var_dump(hexdec("See"));
var_dump(hexdec("ee"));
// both print "int(238)"

var_dump(hexdec("that")); // print "int(10)"
var_dump(hexdec("a0")); // print "int(160)"
?>

Anmerkungen

Hinweis:
Die Funktion kann nun auch Werte umwandeln, die zu groß für den Typ int der jeweiligen Plattform sind, das Ergebnis wird dann als float zurückgegeben.

Siehe auch

dechex() - Wandelt von dezimal zu hexadezimal um
bindec() - Wandelt von binär zu dezimal um
octdec() - Wandelt von oktal zu dezimal um
base_convert() - Wandelt einen numerischen Wert zwischen verschiedenen Zahlensystemen um

add a note

User Contributed Notes 31 notes

down

hafees at msn dot com ¶

14 years ago


Use this function to convert a hexa decimal color code to its RGB equivalent. Unlike many other functions provided here, it will work correctly with hex color short hand notation.

Also, if a proper hexa decimal color value is given (6 digits), it uses bit wise operations for faster results.

For eg: #FFF and #FFFFFF will produce the same result

<?php
/**
 * Convert a hexa decimal color code to its RGB equivalent
 *
 * @param string $hexStr (hexadecimal color value)
 * @param boolean $returnAsString (if set true, returns the value separated by the separator character. Otherwise returns associative array)
 * @param string $seperator (to separate RGB values. Applicable only if second parameter is true.)
 * @return array or string (depending on second parameter. Returns False if invalid hex color value)
 */                                                                                                 
function hex2RGB($hexStr, $returnAsString = false, $seperator = ',') {
    $hexStr = preg_replace("/[^0-9A-Fa-f]/", '', $hexStr); // Gets a proper hex string
    $rgbArray = array();
    if (strlen($hexStr) == 6) { //If a proper hex code, convert using bitwise operation. No overhead... faster
        $colorVal = hexdec($hexStr);
        $rgbArray['red'] = 0xFF & ($colorVal >> 0x10);
        $rgbArray['green'] = 0xFF & ($colorVal >> 0x8);
        $rgbArray['blue'] = 0xFF & $colorVal;
    } elseif (strlen($hexStr) == 3) { //if shorthand notation, need some string manipulations
        $rgbArray['red'] = hexdec(str_repeat(substr($hexStr, 0, 1), 2));
        $rgbArray['green'] = hexdec(str_repeat(substr($hexStr, 1, 1), 2));
        $rgbArray['blue'] = hexdec(str_repeat(substr($hexStr, 2, 1), 2));
    } else {
        return false; //Invalid hex color code
    }
    return $returnAsString ? implode($seperator, $rgbArray) : $rgbArray; // returns the rgb string or the associative array
} ?>

OUTPUT:

hex2RGB("#FF0") -> array( red =>255, green => 255, blue => 0)
hex2RGB("#FFFF00) -> Same as above
hex2RGB("#FF0", true) -> 255,255,0
hex2RGB("#FF0", true, ":") -> 255:255:0

down

Ultimater at gmail dot com ¶

15 years ago


hexdec doesn't accept numbers following the period.
What if you have a number like c20.db18?
<?php
function floatinghexdec($str)
{
    list($intgr,$hex)=explode('.',$str,2);
    $intgr=ereg_replace("[^A-Fa-f0-9]", "", $intgr);
    $hex=ereg_replace("[^A-Fa-f0-9]", "", $hex);
    $answer=0;
    for($i=0;$i < strlen($hex); $i++)
    {
        $digit=hexdec(substr($hex,$i,1))/16;   // .f is 15/16 because in decimal .9 is 9/10
        $answer += $digit/pow(16,$i);
    }
return hexdec($intgr)+$answer;
}

echo floatinghexdec("ff.ff");//255.99609375
?>

down

brian at sagesport dot com ¶

19 years ago


The issue I've seen with the existing hex to dec conversion routines is the lack of error-trapping.  I stick to the theory that one should try to cover ALL the bases when writing a generalized routine such as this one.  I have a varied background that covers a wide variety of design/development languages, on the web as well as desktop apps.  As such I've seen multiple formats for writing hex colors.

For example, the color red COULD be written as follows:
#ff0000
&Hff0000
#ff
&Hff

Therefore I have written a function that is case-insensitive and takes into account the chance that different developers have a tendency to format hex colors in different ways.

<?php
  function convert_color($hex){
    $len = strlen($hex);
    $chars = array("#","&","H","h");
    $hex = strip_chars($hex, $chars);
    preg_match("/([0-9]|[A-F]|[a-f]){".$len."}/i",$hex,$arr);
    $hex = $arr[0];
    if ($hex) {
      switch($len) {
        case 2:
          $red = hexdec($hex);
          $green = 0;
          $blue = 0;
          break;
        case 4:
          $red = hexdec(substr($hex,0,2));
          $green=hexdec(substr($hex,2,2));
          $blue = 0;
          break;
        case 6:
          $red = hexdec(substr($hex,0,2));
          $green=hexdec(substr($hex,2,2));
          $blue = hexdec(substr($hex,4,2));
          break;       
      };
      $color[success] = true;
      $color[r] = $red;
      $color[g] = $green;
      $color[b] = $blue;
      return $color;
    } else {
      $color[success] = false;
      $color[error] = "unable to convert hex to dec";
    };
  }

  function strip_chars($string, $char){
    $len = strlen($string);
    $count = count($char);
    if ($count >= 2) {
      for ($i=0;$i<=$count;$i++) {
        if ($char[$i]) {
          $found = stristr($string,$char[$i]);
          if ($found) {
            $val = substr($string,$found+1,$len-1);
            $string = $val;
          };
        };
      };
    } else {
      $found = stristr($string,$char);
      if ($found) {
        $val = substr($string,$found+1,$len-1);
      };
    };
    echo $val;
    return $val;
  }

  /* 
    To use simply use the following function call:
      $color = convert_color("#FF");
      this will return the following assoc array if successful:
      *[success] = true
      *[r] = 255
      *[g] = 0
      *[b] = 0

      or copy and paste the following code:
      
      $hex = "FFFFFF"; // Color White
      $color = convert_color($hex);
      var_dump($color);
 */ 
?>

As you can see, the function "convert_color" accepts a hex # in most acceptable formats and returns an associative array.  [success] is set to TRUE if the function succeeds and FALSE if not.  The array members [r], [g] and [b] hold the red,green and blue values respectively.  If it fails, [error] holds a custom error message.

"strip_chars" is a support function written to remove the unwanted characters from the hex string, and sends the concatenated string back to the calling function.  It will accept either a single value or an array of values for the characters to remove.

down

Gabriel Reguly ¶

19 years ago


After esnhexdec from "rledger at gmail dot com",  the esndechex:

<?php
    function esndechex($dec){
         $a = strtoupper(dechex(substr($dec, 1,  2)));
         $b = strtoupper(dechex(substr($dec, 3, 10)));
         return $a . $b;
    }
?>

down

Anonymous ¶

17 years ago


// Função GET Cor Hexadecima e Retorna em RGB
function hexrgb($hexstr, $rgb) {
 $int = hexdec($hexstr);
 switch($rgb) {
        case "r":
        return 0xFF & $int >> 0x10;
            break;
        case "g":
        return 0xFF & ($int >> 0x8);
            break;
        case "b":
        return 0xFF & $int;
            break;
        default:
        return array(
            "r" => 0xFF & $int >> 0x10,
            "g" => 0xFF & ($int >> 0x8),
            "b" => 0xFF & $int
            );
            break;
    }    
}// END GET Cor Hex => RGB

//Uso
 echo hexrgb("1a2b3c", r); // 26
 echo hexrgb("1a2b3c", g); // 43
 echo hexrgb("1a2b3c", b); // 60
//ou

var_dump(hexrgb("1a2b3c", rgb)); //array(3) { ["r"]=>  int(26) ["g"]=>  int(43) ["b"]=>  int(60) }

down

Manithu ¶

17 years ago


This tiny function will return foreground colors (either black or white) in contrast to the color you provide:

<?php

function getContrastColor($color)
{
    return (hexdec($color) > 0xffffff/2) ? '000000' : 'ffffff';
}

?>

This function will return the opposite (negative):

<?php

function negativeColor($color)
{
    //get red, green and blue
    $r = substr($color, 0, 2);
    $g = substr($color, 2, 2);
    $b = substr($color, 4, 2);
    
    //revert them, they are decimal now
    $r = 0xff-hexdec($r);
    $g = 0xff-hexdec($g);
    $b = 0xff-hexdec($b);
    
    //now convert them to hex and return.
    return dechex($r).dechex($g).dechex($b);
}

?>

down

cory at lavacube dot com ¶

19 years ago


A handy little function to convert HEX colour codes to "web safe" colours...

<?php

function color_mkwebsafe ( $in )
{
   // put values into an easy-to-use array
   $vals['r'] = hexdec( substr($in, 0, 2) );
   $vals['g'] = hexdec( substr($in, 2, 2) );
   $vals['b'] = hexdec( substr($in, 4, 2) );

   // loop through
   foreach( $vals as $val )
   {
       // convert value
       $val = ( round($val/51) * 51 );
       // convert to HEX
       $out .= str_pad(dechex($val), 2, '0', STR_PAD_LEFT);
   }

   return $out;
}

?>

Example: color_mkwebsafe('0e5c94');
Produces: 006699

Hope this helps someone out... Happy coding. :-)

down

groobo ¶

19 years ago


It's just a revision to marfastic's ligten_up script, it simply adds/subtracts mod_color to orig_color.
I use it often to adjust tonals rather than brightness only

<?
function mod_color($orig_color, $mod, $mod_color){
    /*
        $orig_color - original html color, hex
        $mod_color - modifying color, hex
        $mod - modifier '+' or '-'
        usage: mod_color('CCCCCC', '+', '000033')
    */
    // does quick validation
    preg_match("/([0-9]|[A-F]){6}/i",$orig_color,$orig_arr);
    preg_match("/([0-9]|[A-F]){6}/i",$mod_color,$mod_arr);
    if ($orig_arr[0] && $mod_arr[0]) {
        for ($i=0; $i<6; $i=$i+2) {
            $orig_x = substr($orig_arr[0],$i,2);
            $mod_x = substr($mod_arr[0],$i,2);
            if ($mod == '+') { $new_x = hexdec($orig_x) + hexdec($mod_x); }
            else { $new_x = hexdec($orig_x) - hexdec($mod_x); }
            if ($new_x < 0) { $new_x = 0; }
            else if ($new_x > 255) { $new_x = 255; };
            $new_x = dechex($new_x);
            $ret .= $new_x;
        }
        return $ret;
    } else { return false; }
}
?>

down

flurinj at gmx dot net ¶

14 years ago


Here My version of converting a hex string to a signed decimal value:

<?php

function hexdecs($hex)
{
    // ignore non hex characters
    $hex = preg_replace('/[^0-9A-Fa-f]/', '', $hex);
    
    // converted decimal value:
    $dec = hexdec($hex);
    
    // maximum decimal value based on length of hex + 1:
    //   number of bits in hex number is 8 bits for each 2 hex -> max = 2^n
    //   use 'pow(2,n)' since '1 << n' is only for integers and therefore limited to integer size.
    $max = pow(2, 4 * (strlen($hex) + (strlen($hex) % 2)));
    
    // complement = maximum - converted hex:
    $_dec = $max - $dec;
    
    // if dec value is larger than its complement we have a negative value (first bit is set)
    return $dec > $_dec ? -$_dec : $dec;
}

?>

down

sneskid at hotmail dot com ¶

12 years ago


If you want to create or parse signed Hex strings:

<?php
// $d should be an int
function sdechex($d) { return ($d<0) ? ('-' . dechex(-$d)) : dechex($d); }

// $h should be a string
function shexdec($h) { return ($h[0] === '-') ? -('0x' . substr($h,1) + 0) : ('0x' . $h + 0); }

// test
$h = sdechex(-123); // string(3) "-7b"
$d = shexdec($h);   // int(-123)
var_dump($h, $d);
?>

Also note that ('0x' . $hexstr + 0) is faster than hexdec()
(Tested on PHP v5.2.17)

down

programacion at mundosica dot com ¶

13 years ago


Here is other function to transform a MAC Address to decimal:

<?php
function get_mac_decimal($mac) {
    $clear_mac = preg_replace('/[^0-9A-F]/i','',$mac);
    $mac_decimal = array();
    for ($i = 0; $i < strlen($clear_mac); $i += 2 ):
        $mac_decimal[] = hexdec(substr($clear_mac, $i, 2));
    endfor;
    return implode('.',$mac_decimal);
}
?>

down

Anonymous ¶

19 years ago


I wondered long time what is the best way to generate RGB-color from HEX-color, and just now i found the simpliest way!

<?php
$hex = "FF00FF";
$rgb = hexdec($hex); // 16711935
?>

I hope this will save your time! :)

down

chuckySTAR ¶

15 years ago


Here's my hexdec function for greater numbers using BC Math

<?php
function bchexdec($hex)
{
    $len = strlen($hex);
    for ($i = 1; $i <= $len; $i++)
        $dec = bcadd($dec, bcmul(strval(hexdec($hex[$i - 1])), bcpow('16', strval($len - $i))));
    
    return $dec;
}

echo bchexdec('ffffffffffffffffffffffffffffffff') . "\n" . (pow(2, 128));
?>

down

Halit YEL - halityesil at globya dot net ¶

15 years ago


RGB to Hex

Hex to RGB

Function



<?PHP



function rgb2hex2rgb($c){

   if(!$c) return false;

   $c = trim($c);

   $out = false;

  if(preg_match("/^[0-9ABCDEFabcdef\#]+$/i", $c)){

      $c = str_replace('#','', $c);

      $l = strlen($c) == 3 ? 1 : (strlen($c) == 6 ? 2 : false);



      if($l){

         unset($out);

         $out[0] = $out['r'] = $out['red'] = hexdec(substr($c, 0,1*$l));

         $out[1] = $out['g'] = $out['green'] = hexdec(substr($c, 1*$l,1*$l));

         $out[2] = $out['b'] = $out['blue'] = hexdec(substr($c, 2*$l,1*$l));

      }else $out = false;

              

   }elseif (preg_match("/^[0-9]+(,| |.)+[0-9]+(,| |.)+[0-9]+$/i", $c)){

      $spr = str_replace(array(',',' ','.'), ':', $c);

      $e = explode(":", $spr);

      if(count($e) != 3) return false;

         $out = '#';

         for($i = 0; $i<3; $i++)

            $e[$i] = dechex(($e[$i] <= 0)?0:(($e[$i] >= 255)?255:$e[$i]));

              

         for($i = 0; $i<3; $i++)

            $out .= ((strlen($e[$i]) < 2)?'0':'').$e[$i];

                  

         $out = strtoupper($out);

   }else $out = false;

          

   return $out;

}



?>



Output



#FFFFFF =>

 Array{

   red=>255,

   green=>255,

   blue=>255,

   r=>255,

   g=>255,

   b=>255,

   0=>255,

   1=>255,

   2=>255

 }

 



#FFCCEE =>

 Array{

   red=>255,

   green=>204,

   blue=>238,

   r=>255,

   g=>204,

   b=>238,

   0=>255,

   1=>204,

   2=>238

 }

CC22FF =>

 Array{

   red=>204,

   green=>34,

   blue=>255,

   r=>204,

   g=>34,

   b=>255,

   0=>204,

   1=>34,

   2=>255

 }



0 65 255 => #0041FF

255.150.3 => #FF9603

100,100,250 => #6464FA





[EDIT BY danbrown AT php DOT net - Contains multiple bugfixes by (ajim1417 AT gmail DOT com) on 27-JAN-2010: Replaces typo in explode() and updates eregi() calls to preg_match().]

down

helpmedalph at gmail dot com ¶

8 years ago


function hex2rgb($hex) {
    if ($hex[0]=='#') $hex = substr($hex,1);
    if (strlen($hex)==3){
        $hex = $hex[0].$hex[0].$hex[1].$hex[1].$hex[2].$hex[2];
    }
    $int = hexdec($hex);
    return array("red" => 0xFF & ($int >> 0x10), "green" => 0xFF & ($int >> 0x8), "blue" => 0xFF & $int);
}

down

jose dot rob dot jr at gmail dot com ¶

15 years ago


I made these functions to pack up to 64 ID's into a mysql unsigned bigint.



ID's cannot repeat, must be <= bit's limit and > 0.



The functions uses php 32 bit's int as unsigned because we don't actually read the number, just the bits. Then 0xFFFFFFFF display -1 but the bit's are there (tested with linux 2.6 i686 and x86_64)



---



This is an other way to make hex to bin conversions:



<?php

function hexbin($hex, $padding = false)

{

    // Validation

    $hex = preg_replace('/^(0x|X)?/i', '', $hex);

    $hex = preg_replace('/[[:blank:]]/', '', $hex);

    if(empty($hex))

    {

        $hex = '0';

    }

    if(!preg_match('/^[0-9A-F]*$/i', $hex))

    {

        trigger_error('Argument is not a hex', E_USER_WARNING);

        return false;

    }

    

    // Conversion

    $bin = '';

    $hex = array_reverse(str_split($hex));

    foreach($hex as $n)

    {

        $n = hexdec($n);

        for($i = 1; $i <= 8; $i <<= 1)

        {

            $bin .= ($i & $n)? '1' : '0';

        }

        if($padding)

        {

            $bin .= ' ';

        }

    }

    return ltrim(strrev($bin));

}



// Tests

echo "<b>Debug:</b> <pre>";



// Randomly choosed padded number

var_dump(hexbin('00FF FF8F 7F3F FF1F', true));

// string(79) "0000 0000 1111 1111 1111 1111 1000 1111 0111 1111 0011 1111 1111 1111 0001 1111"



// Yellow RGB

var_dump(hexbin('0xF8F800'));

// string(24) "111110001111100000000000"



// Green RGB (padded)

var_dump(hexbin('0x008800', true));

//string(29) "0000 0000 1000 1000 0000 0000"



die("\n<br>debug");



?>



Have fun ;D

down

zubfatal, root at it dot dk ¶

19 years ago


This replaces my previous class.
I've added a few more input checks in the rgb2hex function.
Also it returned incorrect hex values for 1-digit values.

color::rgb2hex(array(0,0,0)) would output 000 not 00000.

<?php 

/** 
* Convert colors 
* 
* Usage: 
*  color::hex2rgb("FFFFFF") 
*  color::rgb2hex(array(171,37,37)) 
* 
* @author      Tim Johannessen <root@it.dk> 
* @version     1.0.1 
*/ 

class color { 

    /** 
     * Convert HEX colorcode to an array of colors. 
     * @return      array        Returns the array of colors as array(red,green,blue) 
     */ 
     
    function hex2rgb($hexVal = "") { 
        $hexVal = eregi_replace("[^a-fA-F0-9]", "", $hexVal); 
        if (strlen($hexVal) != 6) { return "ERR: Incorrect colorcode, expecting 6 chars (a-f, 0-9)"; } 
        $arrTmp = explode(" ", chunk_split($hexVal, 2, " ")); 
        $arrTmp = array_map("hexdec", $arrTmp); 
        return array("red" => $arrTmp[0], "green" => $arrTmp[1], "blue" => $arrTmp[2]); 
    } 
     
    /** 
     * Convert RGB colors to HEX colorcode 
     * @return      string        Returns the converted colors as a 6 digit colorcode 
     */ 
    function rgb2hex($arrColors = null) { 
        if (!is_array($arrColors)) { return "ERR: Invalid input, expecting an array of colors"; } 
        if (count($arrColors) < 3) { return "ERR: Invalid input, array too small (3)"; } 
         
        array_splice($arrColors, 3); 
         
        for ($x = 0; $x < count($arrColors); $x++) { 
            if (strlen($arrColors[$x]) < 1) { 
                return "ERR: One or more empty values found, expecting array with 3 values"; 
            } 
             
            elseif (eregi("[^0-9]", $arrColors[$x])) { 
                return "ERR: One or more non-numeric values found."; 
            } 
             
            else { 
                if ((intval($arrColors[$x]) < 0) || (intval($arrColors[$x]) > 255)) { 
                    return "ERR: Range mismatch in one or more values (0-255)"; 
                } 
                 
                else { 
                    $arrColors[$x] = strtoupper(str_pad(dechex($arrColors[$x]), 2, 0, STR_PAD_LEFT)); 
                } 
            } 
        } 
         
        return implode("", $arrColors); 
    } 

} 

?>

down

k10206 at naver dot com ¶

17 years ago


<?
function hexrgb($hexstr) {
    $int = hexdec($hexstr);

    return array("red" => 0xFF & ($int >> 0x10), "green" => 0xFF & ($int >> 0x8), "blue" => 0xFF & $int);
}
?>

down

Walter Wlodarski ¶

16 years ago


One of my favourite, multi-purpose, bidirectional solution I wrote many years ago: 

function bgr2rgb($cr) {  // bidirectional
    return (($cr & 0x0000FF) << 16 | ($cr & 0x00FF00) | ($cr & 0xFF0000) >> 16);
}

Which you might want to use as :

function hex2cr($hex) {  // strips any leading characters, like #
    return bgr2rgb(hexdec($hex));
}

function cr2hex($cr) { // the usual HTML format, #rrggbb
    return '#'.str_pad(strtoupper(dechex(bgr2rgb($cr))), 6, '0', STR_PAD_LEFT);
}

And, if like me you tend to mistype function names, the synonym : 

function rgb2bgr($val) { return bgr2rgb($val); }

down

andy at haveland dot com ¶

14 years ago


Here's a short example to convert strings between hex and chars:



<?php

print hextostr("616E647940686176656C616E642E636F6D")."\n";



print strtohex("Knowledge is power")."\n";



function hextostr($x) {

  $s='';

  foreach(explode("\n",trim(chunk_split($x,2))) as $h) $s.=chr(hexdec($h));

  return($s);

}



function strtohex($x) {

  $s='';

  foreach(str_split($x) as $c) $s.=sprintf("%02X",ord($c));

  return($s);

}

?>

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Rosberg - rosberglinhares at gmail dot com ¶

14 years ago


The correct version is:

function bchexdec($hex) {
    static $hexdec = array(
        "0" => 0,
        "1" => 1,
        "2" => 2,
        "3" => 3,
        "4" => 4,
        "5" => 5,
        "6" => 6,
        "7" => 7,
        "8" => 8,
        "9" => 9,
        "A" => 10,
        "B" => 11,
        "C" => 12,
        "D" => 13,
        "E" => 14,
        "F" => 15
    );

    $dec = 0;

    for ($i = strlen($hex) - 1, $e = 1; $i >= 0; $i--, $e = bcmul($e, 16)) {
        $factor = $hexdec[$hex[$i]];
        $dec = bcadd($dec, bcmul($factor, $e));
    }

    return $dec;
}

down

bishop ¶

19 years ago


Bullet-proof hex-to-rgb colour converter like brian at sagesport dot com wanted, just far fewer code lines. As a bonus, gives you the ability to return as string or array:

<?php
    function &hex2rgb($hex, $asString = true) 
    {
        // strip off any leading #
        if (0 === strpos($hex, '#')) { 
            $hex = substr($hex, 1);
        } else if (0 === strpos($hex, '&H')) {
            $hex = substr($hex, 2);
        }       

        // break into hex 3-tuple
        $cutpoint = ceil(strlen($hex) / 2)-1; 
        $rgb = explode(':', wordwrap($hex, $cutpoint, ':', $cutpoint), 3);

        // convert each tuple to decimal
        $rgb[0] = (isset($rgb[0]) ? hexdec($rgb[0]) : 0);
        $rgb[1] = (isset($rgb[1]) ? hexdec($rgb[1]) : 0);
        $rgb[2] = (isset($rgb[2]) ? hexdec($rgb[2]) : 0);

        return ($asString ? "{$rgb[0]} {$rgb[1]} {$rgb[2]}" : $rgb);
    }
?>

Handles 2, 3, and 6 character colour codes with leading # or &H.

down

cgarvis at gmail dot com ¶

18 years ago


Here is my version of hex2rgb for web colors to 24bit colors.

<?php
function hex2rgb_webcolors($hex) {
    $hex = eregi_replace("[^a-fA-F0-9]", "", $hex); 
    switch( strlen($hex) ) {
        case 2:
            $hex = substr($hex,0,2)."0000";
            break;
        case 3:
            $hex = substr($hex,0,1).substr($hex,0,1)
            .substr($hex,1,1).substr($hex,1,1)
            .substr($hex,2,1).substr($hex,2,1);
            break;
        case 4:
            $hex = substr($hex,0,4)."00";
            break;
        case 6:
            break;
        default:
            $hex = 0;
            break;
    }
    return hexdec($hex);
}
?>

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repley at freemail dot it ¶

18 years ago


From color to color to ...... to color with fade effect. Good for dynamic bar chart.

<?php
//MultiColorFade(array hex-colors, int steps)
function MultiColorFade($hex_array, $steps) {

$tot = count($hex_array);
$gradient = array();
$fixend = 2;
$passages = $tot-1;
$stepsforpassage = floor($steps/$passages);
$stepsremain = $steps - ($stepsforpassage*$passages);

   for($pointer = 0; $pointer < $tot-1 ; $pointer++) {
 
       $hexstart = $hex_array[$pointer];
       $hexend = $hex_array[$pointer + 1];

       if($stepsremain > 0){
           if($stepsremain--){
               $stepsforthis = $stepsforpassage + 1;
           }
       }else{
           $stepsforthis = $stepsforpassage;
       }
    
       if($pointer > 0){
           $fixend = 1;         
       }
    
       $start['r'] = hexdec(substr($hexstart, 0, 2));
       $start['g'] = hexdec(substr($hexstart, 2, 2));
       $start['b'] = hexdec(substr($hexstart, 4, 2));

       $end['r'] = hexdec(substr($hexend, 0, 2));
       $end['g'] = hexdec(substr($hexend, 2, 2));
       $end['b'] = hexdec(substr($hexend, 4, 2));
 
       $step['r'] = ($start['r'] - $end['r']) / ($stepsforthis);
       $step['g'] = ($start['g'] - $end['g']) / ($stepsforthis);
       $step['b'] = ($start['b'] - $end['b']) / ($stepsforthis);
    
       for($i = 0; $i <= $stepsforthis-$fixend; $i++) {
 
           $rgb['r'] = floor($start['r'] - ($step['r'] * $i));
           $rgb['g'] = floor($start['g'] - ($step['g'] * $i));
           $rgb['b'] = floor($start['b'] - ($step['b'] * $i));
 
           $hex['r'] = sprintf('%02x', ($rgb['r']));
           $hex['g'] = sprintf('%02x', ($rgb['g']));
           $hex['b'] = sprintf('%02x', ($rgb['b']));
  
           $gradient[] = strtoupper(implode(NULL, $hex));
       }
   }
 
   $gradient[] = $hex_array[$tot-1];
 
return $gradient;
}
//end MultiColorFade()

//start test
$multi_hex_array = array();
$multi_hex_array[] = array('FF0000','FFFF00');
$multi_hex_array[] = array('FF0000','FFFF00','00FF00');
$multi_hex_array[] = array('FF0000','FFFF00','00FF00','00FFFF');
$multi_hex_array[] = array('FF0000','FFFF00','00FF00','00FFFF','0000FF');
$multi_hex_array[] = array('FF0000','FFFF00','00FF00','00FFFF','0000FF','000000');
$multi_hex_array[] = array('FF0000','FFFF00','00FF00','00FFFF','0000FF','000000','FFFFFF');

foreach($multi_hex_array as $hex_array){

   $totcolors = count($hex_array);
   $steps = 44;

   $a = MultiColorFade($hex_array, $steps);
   $tot = count($a);

   $table = '<table border=1 width="300">' . "\n";

   for ($i = 0; $i < $tot; $i++){
       $table .= ' <tr><td bgcolor="' . $a[$i] . '">' . ($i+1) .'</td><td><pre>' . $a[$i] . '</pre></td></tr>' . "\n";
   }
 
   $table .= '</table><br /><br />';
 
   echo '<br />Demanded steps = ' . $steps . '<br />';
   echo 'Returned steps = ' . $tot;
 
   if($steps == $tot){
       echo '<br />OK.' . $steps . ' = ' . $tot . '<br />';
   }else{
       echo '<br /><span style="color:#FF0000">FAILED! Demanded steps and returned steps are NOT equal!: ' . $steps . ' != ' . $tot . '</span><br />';
   }

   echo $table;
 
}
//end test
?>

Repley.

down

detrate at hotmail dot com ¶

19 years ago


I made this for a little phpbb mod.  It was used to take the hex value from the database and make a color 20 (in decimal) less, resulting a darker color.

EXAMPLE: #336699 to #1f5285

<?php

$row1 = "336699"; // color
$c = 20;          // difference value

$rgb = array(substr($row1,0,2), substr($row1,2,2), substr($row1,4,2));

for($i=0; $i < 3; $i++)
{
  if((hexdec($rgb[$i])-$c) >= 0)
  {
   $rgb[$i] = hexdec($rgb[$i])-$c;

   $rgb[$i] = dechex($rgb[$i]);
    if(hexdec($rgb[0]) <= 9)
     $rgb[$i] = "0".$rgb[$i];
  } else {
    $rgb[$i] = "00";
  }
}

$row2 = $rgb[0].$rgb[1].$rgb[2];

?>

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joquius at kakugo dot com ¶

16 years ago


Help a hex-stricken string get back to normal:



<?php

$str = preg_replace_callback ("/%([a-zA-Z0-9]{2})/", create_function ('$matches', 'return chr (hexdec ($matches[1]));'), $str);

?>

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chrism at four dot net ¶

23 years ago


hexdec from 4.1.0 onwards does not show

the same size limitation and therefore

works differently with large numbers than previous php versions.



To obtain the same results, use:



(int) hexdec (...)

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this1is4me at hotmail dot com ¶

16 years ago


In reply to Amit Yadav's post (hex to binary conversion):

function binfromdec($num) 
{
  $primary = "bit";
  for ($i=1; $i<=16; $i++)
    ${$primary.$i} = 0;
  
  if ($num & 32768)   $bit16  = 1;
  if ($num & 16384)   $bit15  = 1;
  if ($num & 8192)    $bit14  = 1;
  if ($num & 4096)    $bit13  = 1;
  if ($num & 2048)    $bit12  = 1;
  if ($num & 1024)    $bit11  = 1;
  if ($num & 512)     $bit10  = 1;
  if ($num & 256)     $bit9   = 1;
  if ($num & 128)     $bit8   = 1;
  if ($num & 64)      $bit7   = 1;
  if ($num & 32)      $bit6   = 1;
  if ($num & 16)      $bit5   = 1;
  if ($num & 8)       $bit4   = 1;
  if ($num & 4)       $bit3   = 1;
  if ($num & 2)       $bit2   = 1;
  if ($num & 1)       $bit1   = 1;
  
  return ($bit16. $bit15. $bit14. $bit13. $bit12. $bit11. $bit10. $bit9. $bit8. $bit7. $bit6. $bit5. $bit4. $bit3. $bit2. $bit1);
}

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maddddidley at yahoo dot com ¶

16 years ago


Function that combines two rgb colors.

function combineColors($color1, $color2) {
        
        $color1 = str_replace("#", '', $color1);
        $color2 = str_replace("#", '', $color2);
        
        $r1 = hexdec(substr($color1, 0, 2));
        $g1 = hexdec(substr($color1, 2, 2));
        $b1 = hexdec(substr($color1, 4, 2)); 
        
        $r2 = hexdec(substr($color2, 0, 2));
        $g2 = hexdec(substr($color2, 2, 2));
        $b2 = hexdec(substr($color2, 4, 2));
        
        $r3 = ceil(($r1 + $r2) / 2);
        $g3 = ceil(($g1 + $g2) / 2);
        $b3 = ceil(($b1 + $b2) / 2);
        
        
        $color = rgbhex($r3, $g3, $b3);
        return $color = str_replace("#", '', $color);
        
    }

down

ayadav at infoprocorp dot com ¶

19 years ago


From Amit Yadav

Hex to binary conversion

$num = hexdec("20DF");
echo binfromdec($num);

function binfromdec($num) 
{
    if ($num > 32766)    return ("Too Large!");
    if ($num & 16384)    $bit15 = 1;
    if ($num & 8192)    $bit14 = 1;
    if ($num & 4096)    $bit13 = 1;
    if ($num & 2048)    $bit12 = 1;
    if ($num & 1024)    $bit11 = 1;
    if ($num & 512)        $bit10 = 1;
    if ($num & 256)        $bit9 = 1;
    if ($num & 128)        $bit8 = 1;
    if ($num & 64)        $bit7 = 1;
    if ($num & 32)        $bit6 = 1;
    if ($num & 16)        $bit5 = 1;
    if ($num & 8)        $bit4 = 1;
    if ($num & 4)        $bit3 = 1;
    if ($num & 2)        $bit2 = 1;
    if ($num & 1)        $bit1 = 1;

    return ("" . $bit15 . $bit14 . $bit13 . $bit12 . $bit11 . $bit10 . $bit9 . $bit8 . $bit7 . $bit6 . $bit5 . $bit4 . $bit3 . $bit2 . $bit1);

}

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andreas.schmeiler ¶

21 years ago


Here's another hex2bin variant, works pretty well to me.

function hex2bin($hexdata) {
   
   for ($i=0;$i<strlen($hexdata);$i+=2) {
      $bindata.=chr(hexdec(substr($hexdata,$i,2)));
   }
   
   return $bindata;
}

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