arabic2roman.pl

这个简单的perl脚本用来在阿拉伯数字与罗马数字之间互相转换。 程序的功能有限

#! /usr/bin/perl -w

@RS = qw(I V X  L  C   D   M   MMM);  # symbols of Roman numerals
@RV = qw(1 5 10 50 100 500 1000);     # values of Roman numerals
$MAX = 4999;

sub Arabic2Roman {
    my $bs = '', my $i, my ($num) = shift;
    return "not valid" if (($num !~ /^(\d+)$/) || $num > $MAX || $num <= 0);
    for ($i = @RV-1; $i >= 0; ) {     # eg: 9 -> VIIII
        ($num >= $RV[$i]) ? ($num -= $RV[$i], $bs .= $RS[$i]) : $i--;
    }
    for ($i=0; $i<@RV; $i++) {        # eg: VIIII -> VIV
        $bs =~ s/($RS[$i]){4}/$RS[$i]$RS[$i+1]/g;
    }
    $bs;
}

sub Roman2Arabic {
    my ($r, $oldv, $i, $s, $v) = (0, 0);
    foreach $s (reverse split ('', uc $_[0])) {
        $i = 0;
        ($v) = grep ($s eq $RS[$i++], @RV);
        $r += ($v<$oldv)? -$v : ($oldv = $v);
    }
    $r;
}

# for example
foreach (@ARGV) {
    print "$_: ", Arabic2Roman($_), "\n";
}