checking if valid hexadecimal code

[BIOSTALL]

Hey.. i'm trying to check whether a hexadecimal code is valid or not.. ie.. only contains A-F, 0-9. I've been trying to do a 'for' loop, stepping through each letter/number in the hex code and checking whether it is A-f or 0-9 but i'm having a bit of trouble.. Can anyone please suggest another way of doing this??

Many Thanks, BIOSTALL

[drew010]

if (preg_match('/^[a-f0-9]+$/i', $hexstr)) {
  echo 'is valid';
} else {
  echo 'is not valid';
}

[BIOSTALL]

Thank you drew010 🙂

[Weedpacket]

Or [man]ctype_xdigit[/man].