I wonder why most of this thread is talking about file handle safety and none of those even mention what will happen if a line in the file is rm -rf /. (thanks for the posts that did mention "do not use eval". eval is dangerous!)

I would not even consider testing this script without a minimal validation of it's input. A start could be:

use 5.16.3;
use warnings;
use autodie;
open my $in,  "<", "numbers.txt";
open my $out, ">", "sum.txt";
while (<$in>) {
    m{\S}    or  next; # skip empty lines
    m{^\s*#} and next; # skip comment lines
    m{^[-.0-9+*/ ]+$} or die "Line too dangerous to evaluate!"; # . fo
+r floats
    # pattern needs extending for math (sqrt, log, sin, cos, ...) supp
+ort and exponentials with e notation
    # and 'x' for hexadecimal, '(', and ')' for grouping etc etc. Anyw
+ay, it is dangerous.
    # I'd not use eval for safety reasons, but if your validator is st
+rict enough
    my $result = eval $_;
    $@ and die "Invalid expression on line $.";
    print $out $result;
    }
close $in;
close $out;

[download]

Enjoy, Have FUN! H.Merijn

In reply to Re: Summing numbers in a file by Tux
in thread Summing numbers in a file by pvfki

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.