如何在 Perl 正则表达式中提取第 n 个匹配项? [英] How can I extract the nth occurrence of a match in a Perl regex?
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问题描述
是否可以从一串单引号中提取nth个匹配项?
Is it possible to extract the nth match in a string of single-quoted words?
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 ($string2, 3); # Should return 'Perl', with quotes
推荐答案
你可以试试:
sub extract_quoted {
my ($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.
}
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