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如何快速求和文件中的所有数字?

更新时间:2021-09-23 22:21:26

对于 Perl one-liner,它与 Ayman Hourieh 的回答:

For a Perl one-liner, it's basically the same thing as the awk solution in Ayman Hourieh's answer:

 % perl -nle '$sum += $_ } END { print $sum'

如果您对 Perl one-liners 的作用感到好奇,您可以解析它们:

If you're curious what Perl one-liners do, you can deparse them:

 %  perl -MO=Deparse -nle '$sum += $_ } END { print $sum'

结果是程序的一个更冗长的版本,以一种没人会自己编写的形式:

The result is a more verbose version of the program, in a form that no one would ever write on their own:

BEGIN { $/ = "
"; $ = "
"; }
LINE: while (defined($_ = <ARGV>)) {
    chomp $_;
    $sum += $_;
}
sub END {
    print $sum;
}
-e syntax OK

只是为了傻笑,我用一个包含 1,000,000 个数字(在 0 - 9,999 范围内)的文件进行了尝试.在我的 Mac Pro 上,它几乎立即恢复.这太糟糕了,因为我希望使用 mmap 会非常快,但它只是在同一时间:

Just for giggles, I tried this with a file containing 1,000,000 numbers (in the range 0 - 9,999). On my Mac Pro, it returns virtually instantaneously. That's too bad, because I was hoping using mmap would be really fast, but it's just the same time:

use 5.010;
use File::Map qw(map_file);

map_file my $map, $ARGV[0];

$sum += $1 while $map =~ m/(d+)/g;

say $sum;