Math 函数
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hexdec

(PHP 4, PHP 5)

hexdec — 十六进制转换为十进制

说明

number hexdec ( string $hex_string )

返回与 hex_string 参数所表示的十六进制数等值的的十进制数。hexdec() 将一个十六进制字符串转换为十进制数。所能转换的最大数值为 7fffffff，即十进制的 2147483647。PHP 4.1.0 开始，该函数可以处理大数字，这种情况下，它会返回 float 类型。

hexdec() 会忽略所有非十六进制字符。

Example #1 hexdec() 例子

<?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)"
?>

参见 dechex()，bindec()，octdec() 和base_convert()。

Math 函数
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PHP手册
PHP手册 - N: 十六进制转换为十进制

用户评论:

sneskid at hotmail dot com (24-Mar-2012 10:50)

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)

programacion at mundosica dot com (07-Dec-2011 05:50)

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);
}
?>

luisfc at setic dot ufsc dot br (08-Apr-2011 09:51)

Here is a function to transform a MAC Address to decimal.

<?php
function get_mac_decimal($mac) {
    $invalid = array(":", "-", ";", ".", " ");
    $clear_mac = str_replace($invalid, "", $mac);
    $mac_decimal = "";

    for ($i = 0; $i < strlen($clear_mac); $i = $i + 2) {
        $mac_decimal .= hexdec(substr($clear_mac, $i, 2));
        if ($i < strlen($clear_mac) - 2) {
            $mac_decimal .= ".";
        }
    }
    return $mac_decimal;
}
?>

andy at haveland dot com (25-Oct-2010 06:55)

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);
}
?>

hafees at msn dot com (19-Aug-2010 11:31)

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

Rosberg - rosberglinhares at gmail dot com (06-May-2010 04:45)

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;
}

flurinj at gmx dot net (06-Apr-2010 03:13)

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;
}

?>

Halit YEL - halityesil at globya dot net (02-Oct-2009 09:30)

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().]

jose dot rob dot jr at gmail dot com (16-Aug-2009 04:13)

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

Ultimater at gmail dot com (19-Apr-2009 09:54)

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
?>

chuckySTAR (15-Apr-2009 09:55)

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));
?>

eds at edsavenue dot com (28-Mar-2009 12:13)

I tried the example by joquius at kakugo dot com, but it didn't work.  i changed it to the following, which did work.

<?php
$str = preg_replace_callback ("([a-zA-Z0-9]{2})", create_function ('$matches', 'return chr (hexdec ($matches[0]));'), $str);
?>

joquius at kakugo dot com (24-Sep-2008 02:12)

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);
?>

this1is4me at hotmail dot com (27-May-2008 10:46)

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);
}

Walter Wlodarski (31-Jan-2008 09:33)

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); }

maddddidley at yahoo dot com (27-Jan-2008 08:17)

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);
       
    }

Anonymous (14-Nov-2007 04:34)

// Fun??o 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) }

k10206 at naver dot com (27-Oct-2007 05:42)

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

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

venk (16-Jun-2007 11:27)

Reply To Halit Yesil's script:

Great Function!! But, there's a problem with your script if the user passes something with three letters/numbers (eg/ #000).  You need to use str_repeat to duplicate each character.

                if($l == 3){
                    unset($out);
                    $out[0] = $out['r'] = $out['red'] = hexdec(str_repeat(substr($c, 0,1),2));
                    $out[1] = $out['g'] = $out['green'] = hexdec(str_repeat(substr($c, 1,1),2));
                    $out[2] = $out['b'] = $out['blue'] = hexdec(str_repeat(substr($c, 2,1),2));
                }

Manithu (24-Mar-2007 12:23)

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);
}

?>

Halit Yesil mail at halityesil dot com (22-Mar-2007 01:46)

RGB to Hex
Hex to RGB
Function

<?PHP

function rgb2hex2rgb($c){
            if(!$c) return false;
            $c = trim($c);
            $out = false;
            if(eregi("^[0-9ABCDEFabcdef\#]+$", $c)){
                $c = str_replace('#','', $c);
                $l = strlen($c);
                if($l == 3){
                    unset($out);
                    $out[0] = $out['r'] = $out['red'] = hexdec(substr($c, 0,1));
                    $out[1] = $out['g'] = $out['green'] = hexdec(substr($c, 1,1));
                    $out[2] = $out['b'] = $out['blue'] = hexdec(substr($c, 2,1));
                }elseif($l == 6){
                    unset($out);
                    $out[0] = $out['r'] = $out['red'] = hexdec(substr($c, 0,2));
                    $out[1] = $out['g'] = $out['green'] = hexdec(substr($c, 2,2));
                    $out[2] = $out['b'] = $out['blue'] = hexdec(substr($c, 4,2));
                }else $out = false;
               
            }elseif (eregi("^[0-9]+(,| |.)+[0-9]+(,| |.)+[0-9]+$", $c)){
                if(eregi(",", $c))
                    $e = explode(",",$c);
                else if(eregi(" ", $c))
                    $e = explode(" ",$c);
                else if(eregi(".", $c))
                    $e = explode(".",$c);
                else return false;
               
                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;
        }

        echo '#FFFFFF => '.rgb2hex2rgb('#FFFFFF').'<br>';
        echo '#FFCCEE => '.rgb2hex2rgb('#FFCCEE').'<br>';
        echo 'CC22FF => '.rgb2hex2rgb('CC22FF').'<br>';
        echo '0 65 255 => '.rgb2hex2rgb('0 65 255').'<br>';
        echo '255.150.3 => '.rgb2hex2rgb('255.150.3').'<br>';
        echo '100,100,250 => '.rgb2hex2rgb('100,100,250').'<br>';

?>

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

cgarvis at gmail dot com (09-Oct-2006 06:39)

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);
}
?>

Lukasz (Zajonc) Zajaczkowski (18-Aug-2006 09:44)

Function converting HEX to signed DEC

function hex2sdec ($hex)
{
  //how many bytes
  $ib = strlen ($hex) - (strlen ($hex) % $hex)) / $hex;
  if ((strlen ($hex) % 2) > 0)
    $ib = $ib + 1;

  //how many bites
  $ibb = 8 * $ib;

  //search for -1 value (max_uj)
  $buf = '1';
  for ($i = 1; $i <= $ibb - 1; $i++)
  {
    $buf .= '0';
  }
  $max_uj = bindec ($buf);

  //decide a sign, and calculate a value
  if (hexdec ($hex) < $max_uj)
  //+
  {
    $sdec = hexdec ($hex);
  }
  else
  //-
  {
    //search for max value + 1
    //(for ex. if hex = 23ef then max_p1 = ffff + 1)
    $buf = '';
    for ($i = 1; $i <= $ib; $i++)
    {
      $buf .= 'ff';
    }
    $max_p1 = hexdec ($buf) + 1;

    $sdec = hexdec ($hex) - $max_p1;
  }

  return $sdec;
}

repley at freemail dot it (29-May-2006 02:55)

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.

greatwhitepine at NOSPAM dot yahoo dot ca (30-Mar-2006 08:46)

Hex to binary conversion that works for large and small hex numbers.

<?php

function hexbin($str_hex) {
  $str_bin = FALSE;
  for ($i=0; $i < strlen($str_hex); $i++) {
    $str_bin .= sprintf("%04s", decbin(hexdec($str_hex[$i])));
  }
  return $str_bin;
}

$str_hex = "effffff20df";

print "\n           HEX VALUE: $str_hex\n";
printf("   REAL BINARY VALUE: %50s\n", hexbin($str_hex));
printf("CHOPPED BINARY VALUE: %50s\n\n", decbin(hexdec($str_hex)));

?>

ayadav at infoprocorp dot com (28-Dec-2005 08:03)

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);

}

cory at lavacube dot com (28-Oct-2005 09:59)

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. :-)

hajamie@home (24-Oct-2005 03:38)

This function will take a hex $color, e.g. fa34bc and make it the shade you want, e.g. anywhere between 0 and 255. The smaller the number, the darker the output color.  It keeps the color the same, only changing the shade.  

function correctshade($color, $shade)
{
$r = hexdec(substr($color,0,2));
$g = hexdec(substr($color,2,2));
$b = hexdec(substr($color,4,2));
$sum = ($r + $g + $b);
$x = (($shade * 3) - $sum) / $sum;
if ($x >= 0) {
$x = $x + 1;
} else {
$x = 1 + $x;
}
$r = intval($x * $r);
$g = intval($x * $g);
$b = intval($x * $b);
$r = dechex($r);
$g = dechex($g);
$b = dechex($b);
return $r.$g.$b;
}

(09-Oct-2005 06:53)

I needed to get the opposite colors so my website would be soft on the eyes.

<?php
function OppositeHex($color)
{
$r = dechex(255 - hexdec(substr($color,0,2)));
$r = (strlen($r) > 1) ? $r : '0'.$r;
$g = dechex(255 - hexdec(substr($color,2,2)));
$g = (strlen($g) > 1) ? $g : '0'.$g;
$b = dechex(255 - hexdec(substr($color,4,2)));
$b = (strlen($b) > 1) ? $b : '0'.$b;
return $r.$g.$b;
}

//Example
$color = '000000';
echo 'The opposite of #'.$color.' is #'.OppositeHex($color).';
?>

detrate at hotmail dot com (30-Sep-2005 02:38)

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];

?>

Gabriel Reguly (16-Aug-2005 07:24)

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;
    }
?>

djneoform at gmail dot com (20-Jun-2005 05:51)

since i couldn't find one, here's an HEX to ASCII converter..

(takes HEX strings (in ASCII) and converts each two digit HEX code into it's ASCII equivalent)

function hex2ascii($str)
{
    $p = '';
    for ($i=0; $i < strlen($str); $i=$i+2)
    {
        $p .= chr(hexdec(substr($str, $i, 2)));
    }
    return $p;
}

bishop (05-Jun-2005 03:51)

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.

Joey Morwick (02-May-2005 09:07)

I found it helpful to have the inverse / reverse of this function laying around, since I wanted to insert some binary data into an xmlrpc call (it currently craps out when you do that), and I couldn't find one laying around, so here's a simple little function to do that:

function hex2bin($str) {
    $build = '';
    while(strlen($str) > 1) {
        $build .= chr(hexdec(substr($str, 0, 2)));
        $str = substr($str, 2, strlen($str)-2);
    }
    return $build;
}

rledger at gmail dot com (29-Mar-2005 07:59)

To convert a cellular ESN from hexadecimal to decimal, use the following code. The base conversion is different due to the fact that the first two characters of a hexadecimal value must be converted seperately from the remaining six characters.
<?
function esnhexdec($hex){
   $a = sprintf("%03d", hexdec(substr($hex, 0, 2)));
   $b = sprintf("%08d", hexdec(substr($hex, 2, 6)));
   return $a . $b;
}
?>

zubfatal, root at it dot dk (25-Mar-2005 10:36)

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);
    }

}

?>

brian at sagesport dot com (22-Mar-2005 05:08)

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.

groobo (10-Feb-2005 07:46)

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; }
}
?>

(19-Jan-2005 05:33)

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! :)

marfastic (10-Dec-2004 03:14)

Here is a function to brighten up any color:

function lighten_up($orig_color, $fraction_denom){
            // return the color between the color and white
            // based on the fraction denom that is passed
           
            if(!isset($fraction_denom))
                $fraction_denom = 2;
            $highest_val = hexdec("FF");
            $r = hexdec(substr($orig_color,0,2));
            $r = ($highest_val-$r)/$fraction_denom + $r;
            $g = hexdec(substr($orig_color,2,2));
            $g = ($highest_val-$g)/$fraction_denom + $g;
            $b = hexdec(substr($orig_color,4,2));
            $b = ($highest_val-$b)/$fraction_denom + $b;
            return dechex($r) . dechex($g) . dechex($b);
        }

_meto ALT+q web.de (08-May-2004 05:00)

Damn, this took me some real long time! Maybe it's helpfull for those who even have no idea of color-Schemes like me ;)

If u want to generate PDF's for Print Offices u need to set all the colors in CMYK.

Here is a Function that will convert RGB to CMYK

<?
function hex2rgb($hex) {
  $color = str_replace('#','',$hex);
  $rgb = array('r' => hexdec(substr($color,0,2)),
               'g' => hexdec(substr($color,2,2)),
               'b' => hexdec(substr($color,4,2)));
  return $rgb;
}

function rgb2cmyk($var1,$g=0,$b=0) {
   if(is_array($var1)) {
      $r = $var1['r'];
      $g = $var1['g'];
      $b = $var1['b'];
   }
   else $r=$var1;
   $cyan    = 255 - $r;
   $magenta = 255 - $g;
   $yellow  = 255 - $b;
   $black   = min($cyan, $magenta, $yellow);
   $cyan    = @(($cyan    - $black) / (255 - $black)) * 255;
   $magenta = @(($magenta - $black) / (255 - $black)) * 255;
   $yellow  = @(($yellow  - $black) / (255 - $black)) * 255;
   return array('c' => $cyan / 255,
                'm' => $magenta / 255,
                'y' => $yellow / 255,
                'k' => $black / 255);
}

$color=rgb2cmyk(hex2rgb('#FF0000'));
pdf_setcolor($pdf, "both", "cmyk", $color['c'], $color['m'], $color['y'], $color['k']);
?>

U can call it with parameters (r,g,b) or just with an array(r,g,b) that contains these values.

Hope it works correct. All testing was fine.

gelado at ip3 dot com (29-Aug-2003 12:30)

Another hex to decimal converter, up to the precision of PHP floats.

function longhex($hex)
{
    $dec = 0;
    $bitval = 1;
    for($pos = 1; $pos <= strlen($hex); $pos++) {
        $dec += hexdec(substr($hex, -$pos, 1)) * $bitval;
        $bitval *= 16;
    }
    return($dec);
}

henrique at recidive dot com (27-May-2003 11:43)

Function to convert a string with hexadecimal colors to an associative array with RGB values:

<?
function hex2dec($hex) {
  $color = str_replace('#', '', $hex);
  $ret = array(
    'r' => hexdec(substr($color, 0, 2)),
    'g' => hexdec(substr($color, 2, 2)),
    'b' => hexdec(substr($color, 4, 2))
  );
  return $ret;
}

/*** Example:
print_r(hex2dec('3D58BE'));

or

print_r(hex2dec('#3D58BE'));

will return

Array
(
  [r] => 61
  [g] => 88
  [b] => 190
)
***/
?>

Thanks !

Henrique Recidive

andreas.schmeiler (05-Feb-2003 01:59)

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;
}

chrism at four dot net (15-Dec-2001 06:02)

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 (...)

andychase at yahoo dot com (18-Jan-2001 02:32)

For hex numbers larger than 7FFFFFFF (E.G. PalmOS dates in seconds elapsed since 01/01/1904), I came up with this:

<?php
function bighexdec($hexnumber){

    $numlength = strlen($hexnumber);

    $decnumber = 0;

    for($x = 1; $x <= $numlength; $x++){

        $place = $numlength - $x;
       
        $operand = hexdec(substr($hexnumber,$place,1));
           
        $exponent = pow(16,$x-1);

        $decValue = $operand * $exponent;
   
        $decnumber += $decValue;

    }
    return $decnumber;
}
?>