Главная | Руководство по MySQL | MySQL Manual | Документация к HTTP серверу Apache | Apache HTTP Server Documentation | downloads | faq

искать  Язык: Английский


dechex

(PHP 4, PHP 5)

dechexDecimal to hexadecimal

Описание

string dechex ( int $number )

Returns a string containing a hexadecimal representation of the given number argument. The largest number that can be converted is 4294967295 in decimal resulting to "ffffffff".

Список параметров

number

Decimal value to convert

Возвращаемые значения

Hexadecimal string representation of number

Примеры

Пример #1 dechex() example

<?php
echo dechex(10) . "\n";
echo 
dechex(47);
?>

Результат выполнения данного примера:

a
2f

Смотрите также


User Contributed Notes
dechex
jbleau at gmail dot com
29-Oct-2008 10:23
I was confused by dechex's size limitation. Here is my solution to the problem. It supports much bigger values, as well as signs.

<?php
function dec_to_hex($dec)
{
   
$sign = ""; // suppress errors
   
if( $dec < 0){ $sign = "-"; $dec = abs($dec); }

   
$hex = Array( 0 => 0, 1 => 1, 2 => 2, 3 => 3, 4 => 4, 5 => 5,
                 
6 => 6, 7 => 7, 8 => 8, 9 => 9, 10 => 'a',
                 
11 => 'b', 12 => 'c', 13 => 'd', 14 => 'e',   
                 
15 => 'f' );
       
    do
    {
       
$h = $hex[($dec%16)] . $h;
       
$dec /= 16;
    }
    while(
$dec >= 1 );
   
    return
$sign . $h;
}
?>
mountarreat at gmail dot com
11-May-2008 04:55
I was challenged by a problem with large number calculations and conversion to hex within php. The calculation exceeded unsigned integer and even float range. You can easily change it for your needs but it is, thanks to bcmath, capable of handling big numbers via string. This function will convert them to hex.

In this specific example though, since I use it for game internals that can only handle 32 bit numbers, it will truncate calculations at 8 digits. If the input is 1 for example it will be filled up with zeros. Output 00000001h.

Of course I don't claim it to be a good one, but it works for me and my purpose. Suggestions on faster code welcome!

<?php
// Turns numbers into 32-bit hex string; Fills up zeros
function lrgDec2Hex($number)
{
   
$i = 0;
   
$hex = array();

    while(
$i < 8) {
        if(
$number == 0) {
           
array_push($hex, '0');
        }
        else {
           
array_push($hex, strtoupper(dechex(bcmod($number, '16'))));
           
$number = bcdiv($number, '16', 0);
        }
       
$i++;
    }
   
krsort($hex);
    return
implode($hex);
}
?>
sjaak at spoilerfreaks dot com
09-Mar-2007 03:28
To force the correct usage of 32-bit unsigned integer in some functions, just add '+0'  just before processing them.

for example
<?php echo(dechex("2724838310")); ?>
will print '7FFFFFFF'
but it should print 'A269BBA6'

When adding '+0' php will handle the 32bit unsigned integer
correctly
<?php echo(dechex("2724838310"+0)); ?>
will print 'A269BBA6'
brent
16-Dec-2006 07:33
Be very careful calling dechex on a number if it's stored in a string.

For instance:

The max number it can handle is 4294967295 which in hex is FFFFFFFF, as it says in the documentation.

dechex(4294967295) => FFFFFFFF //CORRECT

BUT, if you call it on a string of a number, it casts to int, and automatically gives you the largest int it can handle.

dechex('4294967295') => 7FFFFFFF //WRONG!

so you'll need to cast to a float:

dechex((float) '4294967295') => FFFFFFFF //CORRECT

This took me FOREVER to figure out, so hopefully I just saved someone some time.
foros at basnek dot com
24-Jul-2006 04:13
I leave code blocks them that I have made to be able to replace the content of certain blocks of JS that used eval () I hope serves to them.

<?php
// Convert hex 2 str
// Imput Example: \x68\x6f\x6c\x61\x20\x6d\x75\x6e\x64\x6f
$que=( isset( $_POST['hexadecimal'] ) )?$_POST['hexadecimal']:"";
$valores=explode( "\\\x", $que );
for (
$i=0; $i<count( $valores ) ; $i++) {
    echo
chr hexdec( $valores[$i] ) ) ;
}

// Convert str 2 hex
// Imput Example: hola mundo
$que=( isset( $_POST['ascii'] ) )?$_POST['ascii']:"";
for (
$i=0; $i<strlen( $que ) ; $i++) {
    echo
"\\x".dechex( ord( substr( $que, $i, 1) ) ) ;
}
?>
Mista-NiceGuy at web dot de
28-Dec-2005 01:00
These are functions to convert roman numbers (e.g. MXC) into dec and vice versa.
Note: romdec() does not check whether a string is really roman or not. To force a user-input into a real roman number use decrom(romdec($input)). This will turn XXXX into XL for example.

<?php
   
function decrom($dec){
       
$digits=array(
           
1 => "I",
           
4 => "IV",
           
5 => "V",
           
9 => "IX",
           
10 => "X",
           
40 => "XL",
           
50 => "L",
           
90 => "XC",
           
100 => "C",
           
400 => "CD",
           
500 => "D",
           
900 => "CM",
           
1000 => "M"
       
);
       
krsort($digits);
       
$retval="";
        foreach(
$digits as $key => $value){
            while(
$dec>=$key){
               
$dec-=$key;
               
$retval.=$value;
            }
        }
        return
$retval;
    }

    function
romdec($rom){
       
$digits=array(
           
"I" => 1,
           
"V" => 5,
           
"X" => 10,
           
"L" => 50,
           
"C" => 100,
           
"D" => 500,
           
"M" => 1000
       
);
       
$retval="";
       
$chars=array();
        for(
$i=1;$i<=strlen($rom);$i++){
           
$chars[]=substr($rom,$i-1,1);
        }
       
$step=1;
        for(
$i=count($chars)-1;$i>=0;$i--){
            if(!isset(
$digits[$chars[$i]])){ return "Error!"; }
            if(
$step<=$digits[$chars[$i]]){
               
$step=$digits[$chars[$i]];
               
$retval+=$digits[$chars[$i]];
            }
            else{
               
$retval-=$digits[$chars[$i]];
            }
        }
        return
$retval;
    }

    echo
decrom(romdec("XXXX"));
?>
cory at lavacube dot com
27-Oct-2005 11:45
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. :-)
michael at m-ganzer dot de
18-Jul-2005 01:58
simple, non-recursive way of zerofilling (why making everything complicated, there r more than enough inbuilt functions)

function zfill($n,$a) {
  return str_repeat("0",max(0,$a-strlen($n))).$n;
}

"max(0,..." as multiplier inside of "str-repeat" is preventing an error with negative values, if the string length was already higher than the accuracy parameter for zfill.

have fun! :)
trance4rm
17-Jul-2005 08:08
a bugfix for admin AT bobfrank DOT org' s post

The original was:
<?php
function zeropad($num, $lim)
{
   return (
strlen($num) >= $lim) ? $num : zeropad("0" . $num);
}
?>

I couldn't get it to work, kept getting a "Missing argument 2 for zeropad()" error, even though I called the function with both arguments -- then I noticed the recursive part, and the missing $lim argument.  The code that works is:

<?php
function zeropad($num, $lim)
{
   return (
strlen($num) >= $lim) ? $num : zeropad("0" . $num, $lim);     // $lim was missing from the recursive call

// the function will prefix $num with a zero and recursively call itself
// each recursive call, $num gets one digit bigger until strlen of $num  equals $lim
}
?>
oliver at realtsp dot com
14-Jun-2005 08:46
Warning for use on 64 bit machines! The Extra length matters!

32bit machine:
php -r 'echo dechex(4294967295);'
output: ffffffff

64bit machine:
php -r 'echo dechex(4294967295);'
output: ffffffff

so far it is ok. But for slightly bigger numbers:

32bit machine:
php -r 'echo dechex(4294967296);'
output: 0

64bit machine:
php -r 'echo dechex(4294967296);'
output: 100000000

note the difference!

This is particularly important when converting negative numbers:

64bit machine:
php -r 'echo dechex(-1);'
output: ffffffffffffffff

32bit machine:
php -r 'echo dechex(-1);'
output: ffffffff

If you want your code to be portable to amd64 or xeons (which are now quite popular with hosting companies) then you must ensure that your code copes with the different length of the result for negative numbers (and the max value, although that is probably less critical).
jrisken at mn dot rr dot com
29-May-2005 02:33
A less elegant but (perhaps) faster way to pad is with substr with a negative length argument. I use it in this tiny function which formats computed rgb color codes for style sheets:
<?
function toColor($n)
{
return(
"#".substr("000000".dechex($n),-6));
}
?>
admin AT bobfrank DOT org
02-May-2005 02:28
Here is a very small zeropadding that you can use for numbers:

function zeropad($num, $lim)
{
   return (strlen($num) >= $lim) ? $num : zeropad("0" . $num);
}

zeropad("234",6);

will produce:
000234

zeropad("234",1);

will produce:
234
matt dot smith at email dot ky
21-Apr-2005 04:14
It took me hours, but I've finally figured it all out...

--
To figure up how many lines it'll take to get from,
0000 to FFFF, use this formula:
((hex_length / 2) * 255) + 1

For 0000 to FFFF, this would be: ((4 / 2) * 255) + 1 = 511
For 0000000000 to FFFFFFFFFF, this would be: ((10 / 2) * 255) + 1 = 1276

--
To figure up how many possibilities a certain hex length will give (such as that of an MD5 hash, for example), use this formula:
256^(hex_length / 2)

Like so:
hex = 0123ABCDEF
hex_length = 10
possibilities = 256^(10 / 2)
possibilities = 256^5
possibilities = 1,099,511,627,776

--
And I don't know how useful this next part is, but it's quite nifty. Just set $length to be your hex_length and it'll display all "incrementally-possible" hexadecimals, along with line numbers:

<?php
$length
= 10; // Change this to the total length of your hexadecimal

function array_check($array1, $array2)
{
   
$count1 = count($array1);
   
$count2 = count($array2);
   
    if (
$count1 != $count2)
        return
FALSE;
   
   
$match = 0;
    for (
$i = 0; $i < $count1; $i++)
        if (
$array1[$i] == $array2[$i])
           
$match++;
   
    if (
$match != $count1)
        return
FALSE;
   
    return
TRUE;
}

function
zeropad($num)
{
    return (
strlen($num) == 1) ? '0'.$num : $num;
}

function
zeropad_lineno($num, $length)
{
    while (
strlen($num) < $length)
       
$num = '0'.$num;
   
    return
$num;
}

$hexadecimals = $length / 2;
$possibilities = /*number_format(*/ pow(256, $hexadecimals) /*)*/;

echo
"A hexadecimal of this length ({$length}) has {$possibilities} possibilities.<br>\n";
echo
"<br>\n";

//init
for ($i = 0; $i < $hexadecimals; $i++)
{
   
$x[] = '00';
   
$xint[] = 0;
   
   
$end[] = 'ff';
}

$line = 0;
while ( !(
array_check($x, $end)) ) // while we're not currently at the end (FF..)
{
   
$hexstr = '';
    for (
$i = 0; $i < $hexadecimals; $i++)
    {
       
$x[$i] = dechex($xint[$i]);
       
$hexstr .= zeropad(dechex($xint[$i]));
    }
   
   
$line++;
   
$linestr = zeropad_lineno($line, 8);
    echo
"<code>{$linestr}: {$hexstr}</code><br>\n";
   
   
// hex increment
   
for ($i = ($hexadecimals - 1); $i >= 0; $i--)
    {
       
// increment bit if possible
       
if ($xint[$i] != 255)
        {
           
// increment bit and then break out of the for loop
           
$xint[$i]++;
            break;
        }
    }
}
?>
manithu
29-Mar-2005 08:18
If you want to fade some text from one color to another, use this function:

<?php

function colorFade($text, $color1, $color2, $HTMLelement = 'span')
{
   
//remove leading and trailing whitespaces.
   
$text = trim($text);
   
   
//split the characters of the text to an array.
   
$char = array();
    for (
$i = 0; $i < strlen($text); $i++) {
       
$char[$i] = substr($text, $i, 1);
    }
   
//convert the hexadecimal colors in decimal.
   
$decimalColor = array();
   
//first color
   
$decimalColor[0] = hexdec(substr($color1, 0, 2));
   
$decimalColor[1] = hexdec(substr($color1, 2, 2));
   
$decimalColor[2] = hexdec(substr($color1, 4, 2));
   
//second color
   
$decimalColor[3] = hexdec(substr($color2, 0, 2));
   
$decimalColor[4] = hexdec(substr($color2, 2, 2));
   
$decimalColor[5] = hexdec(substr($color2, 4, 2));
   
   
//formated chars are stored here (the key 0 is for the first
    //char and must not be removed).
   
$newText = array(0 => null);
   
//run over every character except the first and the last,
    //they will be added later.
   
for ($i = 2; $i <= strlen($text)-1; $i++) {
       
//check if the character is only a whitespace. If yes,
        //save the whitespace without adding color and proceed
        //to the next character.
       
if (!trim($char[$i-1])) {
           
$newText[] = $char[$i-1];
            continue;
        }
       
//calculate the (hex) color for this character.
       
$color = array();
       
//red
       
$color[] = dechex(($decimalColor[0] - $decimalColor[3])
                   /
strlen($text) * $i + $decimalColor[3]);
       
//green
       
$color[] = dechex(($decimalColor[1] - $decimalColor[4])
                   /
strlen($text) * $i + $decimalColor[4]);
       
//blue
       
$color[] = dechex(($decimalColor[2] - $decimalColor[5])
                   /
strlen($text) * $i + $decimalColor[5]);
       
       
//check if every color part is 2 chars long, if not, repeat it.
       
foreach ($color as $k => $v) {
            if (
strlen($v) < 2) {
               
$color[$k] = str_repeat($v, 2);
            }
        }
       
//merge the parts to the full hex color.
       
$color = implode($color, '');
       
       
//Save the formated char.
       
$newText[] = '<'.$HTMLelement.' style="color:#'.$color.'">'.
                    
$char[$i-1].'</'.$HTMLelement.'>';
    }
   
//add first char.
   
$newText[0] = '<'.$HTMLelement.' style="color:#'.$color2.'">'.
                 
$char[0].'</'.$HTMLelement.'>';
   
//add last char.
   
$newText[]  = '<'.$HTMLelement.' style="color:#'.$color1.'">'.
                 
$char[strlen($text)-1].'</'.$HTMLelement.'>';
   
   
//merge the characters and return it.
   
return implode($newText, '');
}

?>

$color1 is the start color, $color2 the end color.

I hope this helps somebody.
morten at nilsen dot com
02-Jan-2005 12:30
I see a lot of less-than-optimal functions posted on this page, so I feel I have to give some better examples...
due to the sheer size of this collection, I have made it available on my server, rather than copy/paste it into these comments.

http://ryo-ohki.4th-age.com/demos/able.php
and
http://ryo-ohki.4th-age.com/demos/able.phps

dechex replacement function from above source:
<?php
  define
('BIT_BYTE', 8); // bits per byte
 
define('HEX_BYTE', BIT_BYTE/4); // hex digits in a byte

 
define('BIT_INT' 32); // sizeof(int)
 
define('HEX_INT' BIT_INT / (BIT_BYTE/HEX_BYTE)); // hex digits in an int

 
function i2h($int, $group=HEX_BYTE, $size=HEX_INT, $sep=' ') {
   
$ret = '';
    while(
$size--) {
     
$n=($int>>($size*4)) & 0xf;
     
$ret .= $n>9?chr(55 + $n):$n;
      if(
$size && $size%$group == 0) $ret .= $sep;
    }
    return
$ret;
  }

  echo
i2h(rand(1,2)==1?-mt_rand():mt_rand());
?>
wangster at darkcore dot net
15-Dec-2004 07:36
This function will take a string and convert it into a hexdump.

e.g.

3c666f6e 74207369 7a653d22 33223e4c  <font.size."3">L
6561726e 20686f77 20746f20 62652061  earn.how.to.be.a

function hexdump($string) {
   $hex="";
   $substr = "";
   for ($i=0; $i < strlen($string) ;$i++) {
     if(!($i % 4) && $i != 0) {
       $hex .= " ";
     }
     if(!($i % 16) && $i != 0) {
       $clean = preg_replace("/[^a-zA-Z0-9!-.<>\/]/",".",$substr);
       $hex .= " ".htmlentities($clean)."\n";
       $substr = "";
     }
     $substr .=  $string[$i];
     $hex .= dechex(ord($string[$i]));
   }
   return $hex;
}
12-Dec-2004 03:31
If you need to generate random HEX-color, use this:
<?php
function random_hex_color(){
    return
sprintf("%02X%02X%02X", mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));
}
$hex = random_hex_color(); // 09B826
?>

Enjoy.
11-Dec-2004 09:30
If you need to convert RGB-color into HEX-color, use this:
<?php
function rgb2hex($rgb){
    return
sprintf("%06X", $rgb);
}
$hex = rgb2hex(65280); // 00FF00
?>
Ruben Barkow ( at web dot de)
24-May-2004 06:46
this function generates an hex-colorcode out of a string.
usefull if you want to show a list of words all in different colors, that should remain its color even if the order changes.
(if the string is empty, it gives back a random color)

function word2color($w){
if (strlen($w)==0) return substr('00000' . dechex(mt_rand(0, 0xffffff)), -6);
while (strlen($w)<6) $w.=$w;
$minbrightness=1;  // range from 0 to 15, if this is 0 then for ex. black is allowed
$max_brightness=14; // range from 0 to 15, if this is 15 then for ex. white is allowed
$plus_red=0;    // set one of these to set the probability of one of these colors higher
$plus_green=0;
$plus_blue=0;
for ($i=0; $i<6; $i++) {
    #$r.= '">';// this is a depug mode, to see the color written
    $plus=0;
    if ($plus_red<>0 and $i==0) $plus=$plus_red;
    if ($plus_green<>0 and $i==2) $plus=$plus_green;
    if ($plus_blue<>0 and $i==4) $plus=$plus_blue;
    $c=$w[round(strlen($w)/6*$i)];
    $dec=ord($c)%($max_brightness+$plus-$minbrightness) +$minbrightness+$plus;
    if ($dec>$max_brightness-$minbrightness) $dec=$max_brightness-$minbrightness;
    $r.= strtoupper( dechex($dec) );
}
return $r;
}
admin[TAKETHISOUT] at torsoft dot no-ip dot com
21-Apr-2004 07:01
<?php
/*
here are two functions, some might find them useful (maybe for encoding)
converting string to hex and hex to string:
*/

function strhex($string)
{
   
$hex="";
    for (
$i=0;$i<strlen($string);$i++)
       
$hex.=(strlen(dechex(ord($string[$i])))<2)? "0".dechex(ord($string[$i])): dechex(ord($string[$i]));
    return
$hex;
}
function
hexstr($hex)
{
   
$string="";
    for (
$i=0;$i<strlen($hex)-1;$i+=2)
       
$string.=chr(hexdec($hex[$i].$hex[$i+1]));
    return
$string;
}
?>
daevid at daevid dot com
18-Mar-2004 10:59
Here's my version of a red->yellow->green gradient:

<?php
function colorMeter($percent, $invert = false)
{
   
//$percent is in the range 0.0 <= percent <= 1.0
    //    integers are assumed to be 0% - 100%
             // and are converted to a float 0.0 - 1.0
    //     0.0 = red, 0.5 = yellow, 1.0 = green
    //$invert will make the color scale reversed
    //     0.0 = green, 0.5 = yellow, 1.0 = red
   
    //convert (int)% values to (float)
   
if (is_int($percent)) $percent = $percent * 0.01;
   
   
$R = min((2.0 * (1.0-$percent)), 1.0) * 255.0;
   
$G = min((2.0 * $percent), 1.0) * 255.0;
   
$B = 0.0;
   
    return ((
$invert) ?
sprintf("%02X%02X%02X",$G,$R,$B)
:
sprintf("%02X%02X%02X",$R,$G,$B));
}
//colorMeter
?>

and use it like this:

<TABLE BORDER=1 WIDTH="300">
<?php
for ($i = 0.0; $i <= 1.0; $i += 0.10)
{
   
$RGB = colorMeter($i);
    print
"<TR><TD BGCOLOR='".$RGB."'>".$i."</TD><TD>
<PRE>"
.$RGB."</PRE></TD></TR>\n";
}
?>
</TABLE>

<P>

<TABLE BORDER=1 WIDTH="300">
<?php
for ($i = 0; $i <= 100; $i += 10)
{
   
$RGB = colorMeter(intval($i), true);
    print
"<TR><TD BGCOLOR='".$RGB."'>".$i."</TD><TD>
<PRE>"
.$RGB."</PRE></TD></TR>\n";
}
?>
</TABLE>
thr at recide dot net
10-Feb-2004 12:39
/*
* RGB-Colorcodes(i.e: 255 0 255) to HEX-Colorcodes (i.e: FF00FF)
*/
function rgb2hex($rgb){
    if(!is_array($rgb) || count($rgb) != 3){
        echo "Argument must be an array with 3 integer elements";
        return false;
    }
    for($i=0;$i<count($rgb);$i++){
        if(strlen($hex[$i] = dechex($rgb[$i])) == 1){
            $hex[$i] = "0".$hex[$i];
        }
    }
    return $hex;
}
/* Example */
print_r(rgb2hex(array(10,255,255)));
mina86 at tlen dot pl
05-Feb-2004 05:05
Easiest :P way to create random hex color:

<?php
function rand_color() {
    return
substr('00000' . dechex(mt_rand(0, 0xffffff)), -6);
}
?>
paeppi at actionorg dot de
30-Dec-2003 06:53
Easier way to create random hex color:

<?php

function rand_color() {
   
$hexcolor = dechex(mt_rand(0,16777215));

    while (
strlen($hexcolor) < 6) {
       
$hexcolor = $hexcolor."0";
    }
    return
$hexcolor;
}

echo
"#".rand_color();
?>
huda m elmatsani <justhuda at netscape dot net>
16-Sep-2003 10:36
Create Random Hex Color:

function make_seed() {
   list($usec, $sec) = explode(' ', microtime());
   return (float) $sec + ((double) $usec * 100000);
}

function rand_hex() {
   mt_srand(make_seed());
   $randval = mt_rand(0,255);
   //convert to hex
   return sprintf("%02X",$randval);
}

function random_color(){
   return "#".rand_hex().rand_hex().rand_hex();
}

hme ;)
paeppi at actionorg dot de
04-Aug-2003 02:42
# One example how to convert a decimal number into any other system (here 32 digits -- 0 to v) and how to convert back.
# Just replace the "32" in my functions with the number of digits in "your" system, and continue the replace-lists.
# This is surely not the very best way to do this, but it hopefully helps :-)

function decttw($int_dec) {
    $s = $int_dec;
    while ($i < 19) {
        $exp = pow(32,18 - $i);
        $modulo = fmod($s,$exp);
        $value = ($s - $modulo) / $exp;
        if (($value > 0) && ($start != 1)) {
            $start = 1;
        }
        if ($start == 1) {
            $decs = $value;
            $decs = ereg_replace ("10", "a", $decs);
            $decs = ereg_replace ("11", "b", $decs);
            $decs = ereg_replace ("12", "c", $decs);
            $decs = ereg_replace ("13", "d", $decs);
            $decs = ereg_replace ("14", "e", $decs);
            $decs = ereg_replace ("15", "f", $decs);
            $decs = ereg_replace ("16", "g", $decs);
            $decs = ereg_replace ("17", "h", $decs);
            $decs = ereg_replace ("18", "i", $decs);
            $decs = ereg_replace ("19", "j", $decs);
            $decs = ereg_replace ("20", "k", $decs);
            $decs = ereg_replace ("21", "l", $decs);
            $decs = ereg_replace ("22", "m", $decs);
            $decs = ereg_replace ("23", "n", $decs);
            $decs = ereg_replace ("24", "o", $decs);
            $decs = ereg_replace ("25", "p", $decs);
            $decs = ereg_replace ("26", "q", $decs);
            $decs = ereg_replace ("27", "r", $decs);
            $decs = ereg_replace ("28", "s", $decs);
            $decs = ereg_replace ("29", "t", $decs);
            $decs = ereg_replace ("30", "u", $decs);
            $decs = ereg_replace ("31", "v", $decs);
            $int_value = $int_value.$decs;
        }
        $s = $s - $value * $exp;
        $i++;
    }
    return $int_value;
}

function ttwdec($int_ttw) {
    $digits = strlen($int_ttw);
    while ($i < $digits) {
        $s = substr($int_ttw,$i,1);
        $decs = $s;
        $decs = ereg_replace ("a", "10", $decs);
        $decs = ereg_replace ("b", "11", $decs);
        $decs = ereg_replace ("c", "12", $decs);
        $decs = ereg_replace ("d", "13", $decs);
        $decs = ereg_replace ("e", "14", $decs);
        $decs = ereg_replace ("f", "15", $decs);
        $decs = ereg_replace ("g", "16", $decs);
        $decs = ereg_replace ("h", "17", $decs);
        $decs = ereg_replace ("i", "18", $decs);
        $decs = ereg_replace ("j", "19", $decs);
        $decs = ereg_replace ("k", "20", $decs);
        $decs = ereg_replace ("l", "21", $decs);
        $decs = ereg_replace ("m", "22", $decs);
        $decs = ereg_replace ("n", "23", $decs);
        $decs = ereg_replace ("o", "24", $decs);
        $decs = ereg_replace ("p", "25", $decs);
        $decs = ereg_replace ("q", "26", $decs);
        $decs = ereg_replace ("r", "27", $decs);
        $decs = ereg_replace ("s", "28", $decs);
        $decs = ereg_replace ("t", "29", $decs);
        $decs = ereg_replace ("u", "30", $decs);
        $decs = ereg_replace ("v", "31", $decs);
        $i++;
        $value = $decs * pow(32,($digits - $i));
        $int_value = $int_value + $value;
    }
    return $int_value;
}
m0sh3 at hotmail dot com
30-Jul-2003 12:41
This will can convert decimal of more than 2^48 in any PHP version:

$hex = dechex($dec>>24).dechex($dec & 0xFFFFFF)
allan-wegan at allan-wegan dot de
19-Jul-2003 05:53
now, here is a nice and small function to convert integers to hex strings and it avoids use of the DECHEX funtion because that function changed it's behavior too often in the past (now, in PHP version 4.3.2 it works with numbers bigger than 0x7FFFFFFF correctly, but i need to be backward compatible).

function &formatIntegerForOutput($value) {
    $text = "00000000";
    $transString = "0123456789ABCDEF";
    // handle highest nibble (nibble 7):
        $nibble = $value & 0x70000000;
        $nibble >>= 28;
        if ($value < 0) {
            $nibble = $nibble | 0x00000008;
        }
        $text[0] = $transString[$nibble];
        $value &= 0x0FFFFFFF;
    // nibbles 0 to 6:
        for ($a = 7; $a > 0; $a --) {
            $nibble = $value & 0x0000000F;
            $text[$a] = $transString[$nibble];
            $value >>= 4;
        }
    return $text
}

this function should be not too slow and is really simple.
I don't know, if the DECHEX function in the future will pad it's output to ever be 8 characters in length - so for backward compatibility reasons even in future PHP versions i avoided to use it.
paoligno at tin dot it
15-Mar-2003 03:32
you can use this workaround (raw but simple and efficient)

$string=DecHex($string*1)

bye bye
the_tenth at pandora dot be
29-Sep-2002 09:12
<?

function dec2hex($number) {
$length=16;
$hexval="";
while (
$number>0) {
$remainder=bcmod($number,16);
if (
$remainder<10)
$hexval=$remainder.$hexval;
elseif (
$remainder==10)
$hexval="A".$hexval;
elseif (
$remainder==11)
$hexval="B".$hexval;
elseif (
$remainder==12)
$hexval="C".$hexval;
elseif (
$remainder==13)
$hexval="D".$hexval;
elseif (
$remainder==14)
$hexval="E".$hexval;
elseif (
$remainder==15)
$hexval="F".$hexval;
$number=bcdiv($number,16);
}
while (
strlen($hexval)<$length) $hexval="0".$hexval;
return
$hexval;
}

$tmp = "<table width='643' border='1'>";
$x = 1;
$y = 1;
$z = dec2hex($x);
$q = dec2hex($y);
for (
$i=1;$i<65;$i++){
   
$x= bcpow(2,($i-1));
   
$z = dec2hex($x);
   
$tmp .="<tr><td width='20' align='center' bgcolor='#808080'><font color='#ffffff'>". $i;
   
$tmp .="</font></td><td width='5'>2<sup>". ($i-1) . "</sup></td><td width='2'>=</td></td><td>" . $x . "</td>";
   
$tmp .="<td>".$z."</td><td>".$y."</td><td>".$q."</td></tr>";
   
$y = bcsub(bcpow(2,$i+1),1);
   
$q = dec2hex($y);
   
}
$tmp .= "</table>";
echo
$tmp;
?>
monkyNOSPAM at phpfi dot org dot invalid
24-Sep-2002 02:20
Here's how to use bitwise operations for RGB2hex conversion. This function returns hexadesimal rgb value just like one submitted by gurke@bigfoot.com above.

function hexColor($color) {
  return dechex(($color[0]<<16)|($color[1]<<8)|$color[2]);
}

example:

$col[0] = 25;
$col[1] = 255;
$col[2] = 55;

print hexColor($col);
joost at bingopaleis dot com
28-Apr-2002 04:21
Here are two functions that will convert large dec numbers to hex and vice versa. And I really mean LARGE, much larger than any function posted earlier.

<pre>
// Input: A decimal number as a String.
// Output: The equivalent hexadecimal number as a String.
function dec2hex($number)
{
    $hexvalues = array('0','1','2','3','4','5','6','7',
               '8','9','A','B','C','D','E','F');
    $hexval = '';
     while($number != '0')
     {
        $hexval = $hexvalues[bcmod($number,'16')].$hexval;
        $number = bcdiv($number,'16',0);
    }
    return $hexval;
}

// Input: A hexadecimal number as a String.
// Output: The equivalent decimal number as a String.
function hex2dec($number)
{
    $decvalues = 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');
    $decval = '0';
    $number = strrev($number);
    for($i = 0; $i < strlen($number); $i++)
    {
        $decval = bcadd(bcmul(bcpow('16',$i,0),$decvalues[$number{$i}]), $decval);
    }
    return $decval;
}
</pre>
jfren484 at hotmail dot com
12-Feb-2002 11:47
Here's a function which works for decimal values up to 9007199254740992 (hex 20000000000000).

function dec2hex($dec)
{
  $hex = ($dec == 0 ? '0' : '');

  while ($dec > 0)
  {
    $hex = dechex($dec - floor($dec / 16) * 16) . $hex;
    $dec = floor($dec / 16);
  }

  return $hex;
}
kristoffer at caveo dot se
11-Feb-2002 01:39
Heres a example of dec to html hex gradient. Have fun :)

//Amount of gradients
$l = 20;

//Start color
$start[0] = "255";     //red
$start[1] = "0";     //green
$start[2] = "255";     //blue

//End color
$end[0] = "255";     //red
$end[1] = "255";    //green
$end[2] = "255";    //blue

for ($t = 1; $t < $l;) {

    $x = $x * $t;

    for ($i = 0; $i < 3;) {

        $buffer[$i] = $start[$i] - $end[$i];
        $buffer[$i] = floor($buffer[$i] / $l);
        $rgb[$i] = $start[$i] - ($buffer[$i] * $t);

        if ($rgb[$i] > 255) {

            $rgb[$i] = 255;

        }

        $rgb[$i] = dechex($rgb[$i]);
        $rgb[$i] = strtoupper($rgb[$i]);

        if (strlen($rgb[$i]) < 2) {

            $rgb[$i] = "0$rgb[$i]";

        }

        $i++;

    }

    $color = "$rgb[0]$rgb[1]$rgb[2]";
    echo "$color";
        $t++;

}

?>
 

 
credits | contact