CS 161 - Introduction to Programming with PHP
<?php
// Values of digits in the Roman system:
//
$values=array('I'=>1, 'V'=>5, 'X'=>10, 'L'=>50, 'C'=>100, 'D'=>500, 'M'=>1000);
echo "Enter a Roman number: ";
$roman=trim(fgets(STDIN));
$roman=strtoupper($roman);
$decimal=0;
$length=strlen($roman); // Number of digits in Roman number
$i=0;
while ($i<$length) { // While we have more digits to use...
$d0=$values[$roman[$i]]; // Value of current digit
if ($i+1<$length) { // Digits follow...
$d1=$values[$roman[$i+1]];
if ($d1>$d0) { // Larger values mean we use the pair
$d0=$d1-$d0; // Second-First
$i++; // Don't use this digit again
}
}
$decimal+=$d0;
$i++; // Advance to the next digit
}
echo "$decimal\n";
?>