Converting certain values back and forth is often necessary when developing functions to help your website work the way you want it to. I needed a function that would convert a hex color to rgb and for some reason it took me a while to figure it out.
```
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
}
```

This function works with both shorthand hex codes such as #f00 and longhand hex codes such as #ff0000. It also accepts the number sign (#) just in case. You can see there are two return lines at the end of the function. The first, which is commented out, will return the rgb values separated by a comma. The second, which is the default, will return an array with the rgb values.

So now with this function in place we can use it like so:
```
\$rgb = hex2rgb("#cc0");
print_r(\$rgb);
```

The above function would output:
```
Array ( [0] => 204 [1] => 204 [2] => 0 )
```

Since we are going one way with this, might as well go the other. Here is a function to convert rgb to a hex color:
```
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 (#)
}
```

This function works like so:
```
\$rgb = array( 255, 255, 255 );
\$hex = rgb2hex(\$rgb);
echo \$hex;
```

The above function would output:
```
#ffffff
```