Brian P. Giroux wrote: > I am just learning PHP and as a practical exercise I've been working on > a set of functions to process and manipulate what I call "normalized > number" (ISBNs, EANs, UPCs, etc...) > > My ultimate goal is to create a normnum class and child classes for the > different types of numbers. > > Because of my line of work, I am mostly interested in ISBN-10s, > ISBN-13s, EANs and UPCs, but it can also be expanded to credit card > numbers, Canadian Social Insurance Numbers, and many more. > > So far I have functions to validate ISBN-10s and EANs although I've run > into a bit of a wall with the digit_sum function as explained in the B: > section of that functions header comments. if you want to turn the direction around reverse the string before you start the loop: http://php.net/manual/en/function.strrev.php personally I would turn the string into an array of chars (which you can then also reverse as need be) and then do a foreach loop on it ('array index'+1 can be used to determine position) ... personal preference. anyway take a look at these functions: http://php.net/manual/en/function.str-split.php http://php.net/array_reverse http://php.net/foreach > > If anyone can help me out with that or provide any other advice about > the rest of it, I'd be grateful. keep commenting all your code to that extent! you do us proud :-) > > The file can be found at http://www.senecal.ca/normnums.php.txt > > Thanks. -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
