How do I insert multilines in Perl regexps?

Question

我正在使用正则表达式来移动文本块，但它仅删除单行-要删除多行，我应该包括哪些内容？

Answer 1

You are probably looking for /<!--\\[perl\\](.*?)-->/s

Use option switch /s

It treats string as a single line.

"." (dot) will match any character at all, including newline.

Answer 2

There are two things that often trip people up when trying to make regexes work across multiple lines.

The first is the fact that a dot in a regex doesn't match a newline unless you use the /s option on your m// or s/// operator.

The second is that if you're processing a text file a line at a time (perhaps with while (<$filehandle>) { ... } ) then each time round the loop you only have a single line of text to match against. You'll need to read the whole file in at once (perhaps using $text = do { local $/; <$filehandle>}; ).

Answer 3

#!/usr/bin/env perl

use strict; use warnings;

{
    local $/ = '-->';
    while (my $chunk = <DATA>) {
        $chunk =~ s/<!-- \[perl\] (.*) --> \z//sx;
        print $chunk;
    }
}

__DATA__
<!--[perl]

my $x = 5;
my $y = 3;
say $x + $y

-->

<!--[not]

const char *s = "This is not Perl ;-)";

-->

By judiciously altering the input record separator , you can ensure that every chunk you read ends with the string "-->" . Then, it's a matter of ensuring . can match line endings by supplying the /s flag to your substitution operator.

Output:

<!--[not]

const char *s = "This is not Perl ;-)";

-->

You can also remove leading/trailing space from the chunks if that matters.