"George Pitcher" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> That's great, but what about the reverse: Roman to Arabic?
>
> George in Oxford
// NOTE: the order of the table is
// important! I will use greedy parsing,
// so (for example) IX and IV must precede
// I to parse correctly.
$RomanTable = array(
"M" => 1000,
"CM" => 900,
"D" => 500,
"CD" => 400,
"C" => 100,
"XC" => 90,
"L" => 50,
"XL" => 40,
"X" => 10,
"IX" => 9,
"V" => 5,
"IV" => 4,
"I" => 1
);
function MatchClause($needle, $haystack) {
// These two tests are probably just paranoia,
// but - hey, I'm paranoid. ;-)
if (strlen($haystack) < 1)
return false;
if (strlen($haystack) < strlen($needle))
return false;
return( strncasecmp($needle, $haystack, strlen($needle)) == 0 );
}
function RemoveClause($needle, $haystack) {
return( substr($haystack, strlen($needle)) );
}
function RomanToInt($str) {
global $RomanTable;
$sum = 0;
do
{
$done = true;
foreach($RomanTable as $clause => $value)
if ( MatchClause($clause, $str) ) {
$sum += $value;
$str = RemoveClause($clause, $str);
$done = false;
break;
}
}
while ($done == false);
return($sum);
}
NOTE! This algorithm is sufficient but not complete -
it will correctly translate all legal Roman-numeral strings,
but cannot detect illegal strings.
--
Hugh Bothwell [EMAIL PROTECTED] Kingston ON Canada
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