If I want to read array elements from lines of input, and I intend to treat each element as a numeric value, I'd load the array from the file like this (assuming that the input is coming from STDIN or from any file(s) named on the command line when I run the script): 
use Scalar::Util 'looks_like_number';

my @array;
while (<>) {
    chomp;
    if ( looks_like_number( $_ )) {
        push @array, $_;
    }
    else {  # skip this part if you don't care to know about bad input
+...
        warn "Unusable input line skipped: $_\n";
    }
}

[download]
It doesn't matter to me what the input looks like or where it comes from. When I expect it to be of a certain type, I test to see that it really is that type before I actually use it (i.e. I seldom treat data files or STDIN as "trusted" sources).

UPDATE: Having played with that snippet a bit, I'm happy to notice that leading and trailing whitespace characters do not affect the results of "looks_like_number()" (i.e. it returns true for " 123 ", "\t-456\n", and so on). The same is true for arithmetic operators: you can add, subtract, multiply and divide numeric strings that have leading and trailing whitespace.

In reply to Re: Update: problem with scalar by graff
in thread Update: problem with scalar by sargg55

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.