Showing entries with tag "capture".

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Perl: Array of all regexp captures

Perl v5.25.7 added support for the @{^CAPTURE} variable which wrapped all the regexp parenthesis captures up into an array. If you need this functionality in an older version of Perl you can use this function:

my $str =  "Hello Jason Doolis";
$str    =~ /Hello (\w+) (\w+)/;

my @captures = get_captures(); # ("Jason", "Doolis")
sub get_captures {
    no strict 'refs';

    my $last_idx = scalar(@-) - 1;
    my @arr      = 1 .. $last_idx;
    my @ret      = map { $$_; } @arr;

    return @ret;
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Perl: Named captures in regexps

In a regular expression you can capture strings into variables using the default syntax:

$str = "2020-05-20";
$str =~ m/(\d{4})-(\d{2})-(\d{2})/;

printf("Year: %s Month: %s Day: %s\n", $1, $2, $3);

In a more complex regular expression/string things may move around. In this case it's better to use named captures instead of numeric captures. This can be done by using the (?<name>) syntax. This will capture that parenthesis pair in to the hash %+ with the name specified.

$str = "2020-05-20";
$str =~ m/(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})/;

printf("Year: %s Month: %s Day: %s\n", $+{year},$+{month},$+{day});

Using named captures you can easily update your regular expression if the position of elements in your string change.

Note: If you use named captures, Perl also populates the numeric equivalent.

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