php将16进制转换成10进制的函数hexdec

jed , 2006-10-2 16:58 , 代码编程 , 评论(0) , 阅读(7596) , Via 本站原创

hexdec
(PHP 3, 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() 将遇到的所有非十六进制字符替换成 0。这样，所有左边的零都被忽略，但右边的零会计入值中。例子 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()。

add a note User Contributed Notes

ayadav at infoprocorp dot com
28-Dec-2005 04:03
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
29-Oct-2005 04:59
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 10:38
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 01:53
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 09:38
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
17-Aug-2005 02:24
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
21-Jun-2005 12:51
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 10:51
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
03-May-2005 04:07
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 $build;
}
rledger at gmail dot com
29-Mar-2005 03:59
To convert a cellular ESN from hexadecimal to decimal, use the following code. The base conversion is different due to the fact that the first two characters of a hexadecimal value must be converted seperately from the remaining six characters.
<?
function esnhexdec($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 06:36
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
23-Mar-2005 01:08
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
11-Feb-2005 03:46
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; }
}
?>
20-Jan-2005 01:33
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 11:14
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
09-May-2004 12:00
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 07:30
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
28-May-2003 06:43
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 09:59
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
16-Dec-2001 02:02
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 10:32
For hex numbers larger than 7FFFFFFF (E.G. PalmOS dates in seconds elapsed since 01/01/1904), I came up with this:

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;

}
joe at aigraphics dot com
21-Oct-2000 06:32
Here is a fast block of code to convert HTML Style HEX colors to RGB:
--------------------
$r = hexdec(substr($color, 0, 2));
$g = hexdec(substr($color, 2, 2));
$b = hexdec(substr($color, 4, 2));
--------------------
hope it helps you, enjoy.

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