php functions convert hex to rgb and rgb to hex

rgb_to_hex_to_rgb.php

function hex2rgb($hex) {
   $hex = str_replace("#", "", $hex);

   if(strlen($hex) == 3) {
      $r = hexdec(substr($hex,0,1).substr($hex,0,1));
      $g = hexdec(substr($hex,1,1).substr($hex,1,1));
      $b = hexdec(substr($hex,2,1).substr($hex,2,1));
   } else {
      $r = hexdec(substr($hex,0,2));
      $g = hexdec(substr($hex,2,2));
      $b = hexdec(substr($hex,4,2));
   }
   $rgb = array($r, $g, $b);
   //return implode(",", $rgb); // returns the rgb values separated by commas
   return $rgb; // returns an array with the rgb values
}

function rgb2hex($rgb) {
   $hex = "#";
   $hex .= str_pad(dechex($rgb[0]), 2, "0", STR_PAD_LEFT);
   $hex .= str_pad(dechex($rgb[1]), 2, "0", STR_PAD_LEFT);
   $hex .= str_pad(dechex($rgb[2]), 2, "0", STR_PAD_LEFT);

   return $hex; // returns the hex value including the number sign (#)
}

We can do rgb2hex($rgb) simplier

function rgb2hex($rgb)
{
return '#' . sprintf('%02x', $rgb['r']) . sprintf('%02x', $rgb['g']) . sprintf('%02x', $rgb['b']);
}

For hex2rgb you could do

function hex2rgb($hex) {
   $hex = str_replace("#", "", $hex);

   if(strlen($hex) == 3) {
      $r = hexdec($hex[0].$hex[0]);
      $g = hexdec($hex[1].$hex[1]);
      $b = hexdec($hex[2].$hex[2]);
   } else {
      $r = hexdec($hex[0].$hex[1]);
      $g = hexdec($hex[2].$hex[3]);
      $b = hexdec($hex[4].$hex[5]);
   }

   return array($r, $g, $b); // returns an array with the rgb values
}

For hex2rgb you can do:

function hex2rgb($hex) { return sscanf($hex, "#%02x%02x%02x"); }