Perl正则表达式，获取两个字符串之间的字符串

Question

I am new to Perl and trying to use Regex to get a piece of string between two tags that I know will be there in that string. I already tried various answers from stackoverflow but none of them seems to be working for me. Here's my example...

The required data is in $info variable out of which I want to get the useful data

my $info = "random text i do not want\n|BIRTH PLACE=Boston, MA\n|more unwanted random text";

The Useful Data in the above string is Boston, MA . I removed the newlines from the string by $info =~ s/\\n//g; . Now $info has this string "random text i do not want|BIRTH PLACE=Boston, MA|more unwanted random text" . I thought doing this will help me capture the required data easily.

Please help me in getting the required data. I am sure that the data will always be preceded by |BIRTH PLACE= and succeeded by | . Everything before and after that is unwanted text. If a question like this is already answered please guide me to it as well. Thanks.

Answer 1

除了替换周围的所有内容，您还可以搜索/\\|BIRTH PLACE=([^\\|]+)\\n\\|/ ，[^ \\ |] + anything that is not a pipe的anything that is not a pipe一项或多项。

Answer 2

$info =~ m{\|BIRTH PLACE=(.*?)\|} or die "There is no data in \$info?!";
my $birth_place = $1;

That should do the trick.

Answer 3

You know, actually, those newlines might have helped you. I would have gone for an initial regular expression of:

/^\|BIRTH PLACE=(.*)$/m

Using the multiline modifer ( m ) to match ^ at the beginning of a line and $ at the end of it, instead of just matching at the beginning and end of the string. Heck, you can even get really crazy and match:

/(?<=^\|BIRTH PLACE=).+$/m

To capture only the information you want, using lookbehind ( (?<= ... ) ) to assert that it's the birth place information.

Why curse the string twice when you can do it once?

So, in perl:

if ($info =~ m/(?<=^\|BIRTH PLACE=).+$/m) {
    print "Born in $&.\n";
} else {
    print "From parts unknown";
}

Answer 4

You have presumably read this data from a file, which is a bad start. You program should look like this

use strict;
use warnings;

use autodie;

open my $fh, '<', 'myfile';

my $pob;
while (<$fh>) {
  if (/BIRTH PLACE=(.+)/) {
    $pob = $1;
    last;
  }
}

print $pob;

output

Boston, MA