#!/usr/bin/perl -w
use strict;

my $x= '1 2 3 4 5 6 7 8 9 10 11 12 13 14 15';
print "$x\n";
$x =~ m/^(?<weight>\d+)\s*$/g;
#my $weight = $1;
print "$+{weight}\n";
print "Weight:\n" unless $x=~/Gkg\./g;

[download]

I am trying to print each number from variable x. but I am getting an error which says-Use of uninitialized value $+{"weight"} in concatenation (.) or string. I am trying to execute the following example from "https://perldoc.perl.org/perlretut.html#Using-regular-expressions-in-Perl" 

    $metric = 1;  # use metric units
    $x = <FILE>;  # read in measurement
    $x =~ /^([+-]?\d+)\s*/g;  # get magnitude
    $weight = $1;
    if ($metric) { # error checking
        print "Units error!" unless $x =~ /\Gkg\./g;
    }
    else {
        print "Units error!" unless $x =~ /\Glbs\./g;
    }

[download]

Can any body highlight the issue with my code?

In reply to Regular expression by pravakta

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.