Perl 字符串转 Base36

Question

如何在 Perl 中将字符串转换为 Base36 (0-9,az)？

我想使用一对一映射将 IP 地址转换为 base36，这样我就可以在 URL 中使用它们。

127.0.0.1 === 字符串 ==> 127000000001=== base36 ==>

72.98.234.11 === 字符串 ==> 072098234011=== base36 ==>

Answer 1

10 基数还不够好吗？这给出了 [0-4294967295] 之间的数字（1 到 10 位数字）。这仅比我们将从您的方式获得的内容（1 到 8 位数字）稍长一些。

$ perl -E'say unpack "N", pack "C4", split /\./, $ARGV[0]' 127.0.0.1
2130706433

$ perl -E'say unpack "N", pack "C4", split /\./, $ARGV[0]' 72.98.234.11
1214441995

完全可逆：

$ perl -E'say join ".", unpack "C4", pack "N", $ARGV[0]' 2130706433
127.0.0.1

$ perl -E'say join ".", unpack "C4", pack "N", $ARGV[0]' 1214441995
72.98.234.11

您可以使用 CPAN 上的任意数量的模块将该数字转换为 10 以外的其他基数。

base 10: 1-10 digits
base 16: 1-8 digits    # Can be done very efficiently
base 32: 1-7 digits    # Can be done very efficiently
base 36: 1-7 digits
base 62: 1-6 digits
base 64: 1-6 digits    # Can be done very efficiently

基地 16：

sub pack_ip { sprintf "%X", unpack "N", pack "C4", split /\./, $_[0] }

sub unpack_ip { join ".", unpack "C4", pack "N", hex $_[0] }

Base 64：（这应该相当快。即使移植到 C 也会更快。）

my @syms = ('0'..'9', 'A'..'Z', 'a'..'z', '_', '-');
my %syms = map { $sym[$_] => $_ } 0..$#syms;

sub pack_ip {
   my $num = unpack "N", pack "C4", split /\./, $_[0];
   my $base64 = join '', @syms[
      ($num >> 30) & 0x3F,
      ($num >> 24) & 0x3F,
      ($num >> 18) & 0x3F,
      ($num >> 12) & 0x3F,
      ($num >>  6) & 0x3F,
      ($num >>  0) & 0x3F,
   ];
   $base64 =~ s/^A+(?!\z)//;
   return $base64;
}

sub unpack_ip {
   my $num;
   $num = ($num << 6) | $sym{$_}
      for split //, $_[0];
   return join ".", unpack "C4", pack "N", $num;
}