如何在Perl正则表达式中提取第n个匹配项？

发布时间：2020-12-15 21:38:52 所属栏目：大数据来源：网络整理

导读：是否可以在一串单引号词中提取第n个匹配？ use strict;use warnings;my $string1 = "'I want to' 'extract the word' 'Perl','from this string'";my $string2 = "'What about','getting','Perl','from','here','?'";sub extract_quoted { my ($string,$inde

是否可以在一串单引号词中提取第n个匹配？

use strict;
use warnings;

my $string1 = "'I want to' 'extract the word' 'Perl','from this string'";
my $string2 = "'What about','getting','Perl','from','here','?'";

sub extract_quoted { 

    my ($string,$index) = @_;
    my ($wanted) = $string =~ /some_regex_using _$index/;
    return $wanted;
}

extract_wanted ($string1,3); # Should return 'Perl',with quotes
extract_wanted ($string2,with quotes

解决方法

你可以试试：

sub extract_quoted {

        my ($string,$index) = @_;
        while($string =~ /'(.*?)'/g) {
                $index--;
                return $1 if(! $index); # return $1 if index became 0. 
        }
        return; # not found - returns undef or () depending on context.
}

（编辑：李大同）

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