Excel列名変換問題で第２回社内プログラミングコンテストを開催してみた(前編)を素直に書いてみた

excel_util.pl

#!perl
use strict;
use warnings;

my $to_column = shift;
die "first argument is '0' or '1'" unless $to_column == 0 or $to_column == 1;

my $arg = shift or die "Usage: $0 to_column value";
$arg = uc $arg;

my $a_ascii_code = ord 'A';

if ($to_column == 0) {
    my $num = 0;
    for my $n (split //, $arg) {
        my $char_var = ord($n) - $a_ascii_code + 1;
        $num = (26 * $num + $char_var);
    }

    print "$arg => $num\n";
} else {
    my @remains;
    my $num = $arg;
    while ($num > 26) {
        push @remains, ($num % 26);
        $num = int($num / 26);
    }
    push @remains, $num;

    my @chars;
    for my $n (map { $_ - 1 } reverse @remains) {
        push @chars, chr($n + $a_ascii_code);
    }

    printf "%s => %s\n", $arg, join '', @chars;
}

test.log

perl excel_util.pl 0 A
A => 1
perl excel_util.pl 0 Z
Z => 26
perl excel_util.pl 0 AA
AA => 27
perl excel_util.pl 0 XFD
XFD => 16384
perl excel_util.pl 1 26
26 => Z
perl excel_util.pl 1 27
27 => AA
perl excel_util.pl 1 16384
16384 => XFD