Hex to RGB conversion.

hex2rgb.php

<?php

$str = 'ffffff';
    
$chartype = ctype_alnum($str);
$charcount = strlen($str);

if ($charcount === 3 && $chartype) {
    $splitby = 1;
} else if ($charcount === 6 && $chartype) {
    $splitby = 2;
} else {
    exit('invalid hex code format');
}
    
$arr = str_split($str, $splitby);
    
foreach ($arr as $rgbval) {
    if ($splitby === 1) {
        $rgbval = $rgbval . $rgbval;
    }
    $rgbval = hexdec($rgbval);
    $rgb[] = $rgbval;
}
    
echo 'rgb(' . $rgb[0] . ',' . $rgb[1] . ',' . $rgb[2] . ')';