Bug #4991

Roman numeral validation

Details

Request #4991	Roman numeral validation
Submitted	2005-08-04 00:16 UTC
From	joe at joestump dot net
Assigned	pajoye
Status	Wont fix
Package	Validate
PHP Version	Irrelevant
OS	All
Roadmaps	(Not assigned)

Comments

[2005-08-04 00:16 UTC] joe at joestump dot net

Description:
------------
The function Numbers_Roman::toNumber() does not validate
whether or not the given string is even a valid roman numeral.
For instance, XXXXX isn't valid. It should be L.

I'd either create Numbers_Roman::isValid() or add the
validation code to toNumber() and have it return false, 0 or
PEAR_Error. Here is the proper regexp (appears to work great):

^M{0,4}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})$

Maybe this should be part of the Validate package?

Test script:
---------------
<?php

require_once 'Numbers/Roman.php';

echo Numbers_Roman::toNumber('XXXXX')."\n";
echo Numbers_Roman::toNumber('L')."\n";
echo Numbers_Roman::toNumeral(30)."\n";

Expected result:
----------------
First echo should be false, 0 or a PEAR_Error

Actual result:
--------------
It returns 50, which *technically* is true (5 * X = 50), but
the number itself is invalid.