Beefy Boxes and Bandwidth Generously Provided by pair Networks
P is for Practical

Comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
Dear Monks,
doing some exercises from the Alpaca book I noticed a strange behavior of the grep operator.
The exercise was to filter the files smaller than 1000 bytes.
This code (if called with C:\perl\bin>perl N:/TEMP/*):
#!/usr/bin/perl -l use strict; use warnings; @ARGV = map{glob} @ARGV; my @selection = grep { -s < 1000 } @ARGV; print for @selection;
produces the following error message:
Warning: Use of "-s" without parentheses is ambiguous at lin +e 7. Unterminated <> operator at line 7.
If I use the parenthesis it runs ok:
#!/usr/bin/perl -l use strict; use warnings; @ARGV = map{glob} @ARGV; my @selection = grep { (-s) < 1000 } @ARGV; print for @selection;
If I search for files bigger than 1000 the parentheses are not necessary.
It seems that perl interprets the less than sign as a part of a diamond operator.
In the answers part of the book however there is a line exact as my original line without parentheses:
my @smaller_than_1000 = grep { -s < 1000 } @ARGV;
Is it the windows peculiarity which I have here?
Thanks in advance!

In reply to The "<" in the grep block by vagabonding electron

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, 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, 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.
  • Log In?

    What's my password?
    Create A New User
    and all is quiet...

    How do I use this? | Other CB clients
    Other Users?
    Others chilling in the Monastery: (3)
    As of 2017-12-14 03:05 GMT
    Find Nodes?
      Voting Booth?
      What programming language do you hate the most?

      Results (384 votes). Check out past polls.