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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。

hexdec() 会忽略它遇到的任意非十六进制的字符。

参数

hex_string: 要转换的十六进制的字符串

返回值

hex_string 十进制的表示

更新日志

版本	说明
4.1.0	PHP 4.1.0 开始，该函数可以处理 integer 大数字，这种情况下，它会返回 float 类型。

范例

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() - 十进制转换为十六进制
bindec() - 二进制转换为十进制
octdec() - 八进制转换为十进制
base_convert() - 在任意进制之间转换数字

用户评论:

[#1] Ulf [2013-08-20 10:51:16]

Instead of chuckySTAR's cool bchexdec() function you could also just use
base_convert("fffffffffffffffffffffffffffffffff", 16, 10)
to convert hex values of any size to a decimal string.

[#2] holdoffhunger at gmail dot com [2012-06-25 18:29:41]

When given large numbers, the hexdec function automatically converts the value to scientific notation. So, "aa1233123124121241" as a hexadecimal value will be converted to "3.13725790445E+21". If you're converting a hexadecimal value that represents a hash value (md5 or sha), then you need every single bit of that representation to make it useful. By using the number_format function, you can do that perfectly. For example :

<?php // Author: holdoffhunger@gmail.com // Example Hexadecimal // --------------------------------------------- $hexadecimal_string = "1234567890abcdef1234567890abcdef"; // Converted to Decimal // --------------------------------------------- $decimal_result = hexdec($hexadecimal_string); // Print Pre-Formatted Results // --------------------------------------------- print($decimal_result); // Output Here: "2.41978572002E+37" // ..................................... // Format Results to View Whole All Digits in Integer // --------------------------------------------- // ( Note: All fractional value of the // Hexadecimal variable are ignored // in the conversion. ) $current_hashing_algorithm_decimal_result = number_format($decimal_result, 0, '', ''); // Print Formatted Results // --------------------------------------------- print($current_hashing_algorithm_decimal_result); // Output Here: "24197857200151253041252346215207534592" // ..................................... ?>

[#3] sneskid at hotmail dot com [2012-03-24 02:50:59]

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)

[#4] programacion at mundosica dot com [2011-12-06 21:50:47]

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); } ?>

[#5] andy at haveland dot com [2010-10-24 22:55:20]

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); } ?>

[#6] hafees at msn dot com [2010-08-19 03:31:00]

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 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

[#7] Rosberg - rosberglinhares at gmail dot com [2010-05-06 08:45:11]

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;
}

[#8] flurinj at gmx dot net [2010-04-06 07:13:50]

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; } ?>

[#9] Halit YEL - halityesil at globya dot net [2009-10-02 01:30:27]

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().]

[#10] jose dot rob dot jr at gmail dot com [2009-08-15 20:13:26]

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

[#11] Ultimater at gmail dot com [2009-04-19 13:54:21]

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 ?>

[#12] chuckySTAR [2009-04-15 13:55:11]

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)); ?>

[#13] joquius at kakugo dot com [2008-09-24 06:12:30]

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); ?>

[#14] this1is4me at hotmail dot com [2008-05-27 02:46:23]

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);
}

[#15] Walter Wlodarski [2008-01-31 13:33:17]

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); }

[#16] maddddidley at yahoo dot com [2008-01-27 00:17:56]

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);

}

[#17] Anonymous [2007-11-13 20:34:38]

// 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) }

[#18] k10206 at naver dot com [2007-10-27 09:42:49]

<?php function hexrgb($hexstr) { $int = hexdec($hexstr); return array("red" => 0xFF & ($int >> 0x10), "green" => 0xFF & ($int >> 0x8), "blue" => 0xFF & $int); } ?>

[#19] Manithu [2007-03-23 16:23:50]

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); } ?>

[#20] cgarvis at gmail dot com [2006-10-09 10:39:45]

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); } ?>

[#21] repley at freemail dot it [2006-05-28 18:55:32]

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.

[#22] ayadav at infoprocorp dot com [2005-12-28 00:03:32]

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);

}

[#23] cory at lavacube dot com [2005-10-28 13:59:24]

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. :-)

[#24] detrate at hotmail dot com [2005-09-29 18:38:33]

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]; ?>

[#25] Gabriel Reguly [2005-08-16 11:24:37]

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; } ?>

[#26] bishop [2005-06-04 19:51:29]

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.

[#27] zubfatal, root at it dot dk [2005-03-25 02:36:38]

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 class color { 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" => $arrTmp[2]); } function rgb2hex($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); } } ?>

[#28] brian at sagesport dot com [2005-03-22 09:08:05]

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;   }     ?>

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.

[#29] groobo [2005-02-10 11:46:28]

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

<?php function mod_color($orig_color, $mod, $mod_color){ // does quick validation preg_match("/([0-9]|[A-F]){6}/i",$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; } } ?>

[#30] [2005-01-19 09:33:54]

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! :)

[#31] andreas.schmeiler [2003-02-05 05:59:34]

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;
}

[#32] chrism at four dot net [2001-12-15 10:02:37]

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 (...)