Parse RGB string to array [closed]

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Is there any build-in PHP function to get the following result?

    $rgba = "rgba(246, 24, 35, 0.8)";
    $splittedRgba = splitRGB($rgba);

    $rgb = "rgb(246, 24, 35)";
    $splittedRgb = splitRGB($rgb); // splitRGB is the function I need
    /*
        $splittedRgba['r'] = 246;
        $splittedRgba['g'] = 24;
        $splittedRgba['b'] = 35;
        $splittedRgba['a'] = 0.8;

        $splittedRgb['r'] = 246;
        $splittedRgb['g'] = 24;
        $splittedRgb['b'] = 35;
        $splittedRgb['a'] = 1;
    */

There isn't from an arbitrary string, but preg_match() will do the job with an appropriate regexp — Mark Baker
– Mark Baker, Commented Sep 9, 2014 at 14:04
PHP is a toolbox. it contains screwdrivers, hammers, maybe a measuring tape and a pencil. You're expecting it to contain a fully developed house, complete with plumbing and electrical wiring for EVERY possible thing you want it to do. Instead of flailing around looking for a can opener that will cook your thanksgiving dinner and help your kids get into college, you should learn how to use the basic tools PHP does provide to BUILD that all-in-one tool. — Marc B
– Marc B, Commented Sep 9, 2014 at 14:18

raina77ow · Accepted Answer · 2014-09-09 16:10:33Z

9

You can use a preg_match, but you can also use the simpler sscanf function:

$rgba = sscanf("rgba(246, 24, 35, 0.8)", "rgba(%d, %d, %d, %f)");

print_r($rgba);

$rgb = sscanf("rgb(246, 24, 35)", "rgb(%d, %d, %d)");

print_r($rgba);

%d matches a decimal number, %f matches a floating point number.

References:

http://php.net/list

http://php.net/sscanf

Don't expect people to provide you with fully working super functional code. Answers here make clear mistakes you made and should give you an idea helping to solve a more complex problem.

So your part here would be something like:

function parseRGBa($rgba) {
    $rgba = trim(str_replace(' ', '', $rgba));
    if (stripos($rgba, 'rgba') !== false) {
        $res = sscanf($rgba, "rgba(%d, %d, %d, %f)");
    }
    else {
        $res = sscanf($rgba, "rgb(%d, %d, %d)");
        $res[] = 1;
    }
    return array_combine(array('r', 'g', 'b', 'a'), $res);
}

print_r(parseRGBa('rgba(1, 2, 3, 0.5)'));

Demo.

edited Sep 9, 2014 at 16:10

raina77ow

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answered Sep 9, 2014 at 14:06

Daniel W.

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4 Comments

Chris Over a year ago

Not working with $rgb = "rgb(246, 24, 35)";. I don't know if the string starts with rgb or rgba.

Daniel W. Over a year ago

Sorry, I did expect your transfer knowledge to be able to handle the missing code with your own imagination.

raina77ow Over a year ago

@DanFromGermany Very nice approach, just made a couple of adjustments in your code. )

Daniel W. Over a year ago

The array code style [...] doesn't work in PHP prior to version 5.4, but of course you are welcome to extend my answer, good idea there!

hex494D49 · Accepted Answer · 2014-09-09 15:25:49Z

1

Another solution using preg_match_all() function

$rgba = array("r" => 0, "g" => 0, "b" => 0, "a" => 1);
$string = "246, 24, 35, 0.8"; // or "rgba(246, 24, 35, 0.8)"
$i = 0;

preg_match_all('/[0-9.]+/', $string, $color);   
foreach ($rgba as $key => $value) {
  $rgba[$key] = $color[0][$i++] ?: 1;
}

print_r($rgba);

Output:

Array
(
    [r] => 246
    [g] => 24
    [b] => 35
    [a] => 0.8
)

In case you have this format

$string = "246, 24, 35"; // or "rgb(246, 24, 35)"

as expected, the output will be

Array
(
    [r] => 246
    [g] => 24
    [b] => 35
    [a] => 1
)

Working PHP demo

edited Sep 9, 2014 at 15:25

answered Sep 9, 2014 at 14:10

hex494D49

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