PHP 8.1.31 Released!

    hexdec

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

    hexdec — Hexadecimal a decimal

    Descripción

    hexdec(string $hex_string): number

    Devuelve el equivalente decimal del número hexadecimal representado por el argumento cadena_hex. hexdec() convierte un string hexadecimal a un número decimal.

    hexdec() ignora cualquier caracter no hexadecimal que encuentre.

    Parámetros

    hex_string

    El string hexadecimal a convertir

    Valores devueltos

    La representación decimal de hex_string

    Ejemplos

    Ejemplo #1 Ejemplo de hexdec()

    <?php
    var_dump    (hexdec("See"));
    var_dump(hexdec("ee"));
    // ambos imprimen "int(238)"

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

    Notas

    Nota:

    Esta función puede convertir números que son demasiado grandes para caber en el tipo integer de cada plataforma, devolviendo en este caso un valor de tipo float para los valores mayores.

    Ver también

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    User Contributed Notes 31 notes

    up
    30
    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
    up
    3
    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
    ?>
    up
    3
    chrism at four dot net
    22 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 (...)
    up
    5
    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 . $b;
    }
    ?>
    up
    2
    Anonymous
    17 years ago
    // Função GET Cor Hexadecima e Retorna em RGB
    function hexrgb($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) }
    up
    2
    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. :-)
    up
    2
    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; }
    }
    ?>
    up
    6
    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;
    }

    ?>
    up
    3
    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.
    up
    5
    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().]
    up
    3
    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)
    up
    3
    programacion at mundosica dot com
    12 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);
    }
    ?>
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    4
    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! :)
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    6
    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));
    ?>
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    1
    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);
    }
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    2
    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);
    }

    ?>
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    1
    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);
    }

    }

    ?>
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    4
    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);
    }
    ?>
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    2
    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); }
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    1
    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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    1
    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;
    }
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    2
    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
    up
    1
    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.
    up
    2
    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);
    }
    ?>
    up
    2
    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.
    up
    2
    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];

    ?>
    up
    1
    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);
    ?>
    up
    0
    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);
    }
    up
    0
    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);

    }
    up
    0
    ayadav at infoprocorp dot com
    18 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);

    }
    up
    0
    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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