A couple comments:
  1. my $decimals = $ARGV[1] ? $ARGV[1] : 2; won't perform as expected if the user enters 0. You will get expected behavior if you use my $decimals = defined $ARGV[1] ? $ARGV[1] : 2;. You should also swap your $float assignment.
  2. On the same point, if you have v5.10 or greater, you can use the 'defined or' operator (//)to do the same thing: my $decimals = $ARGV[1] // 2;
  3. The & is largely unnecessary in modern Perl; your code functions just fine without it.
  4. I'd be a little gun-shy about using the same variable name in the script level variables as in the subroutine level variables - it's easy to introduce a difficult bug.
  5. You can use list assignment rather than a series of shifts if you want to save a few key strokes, replacing 

      my $float = shift;
  my $dec = shift;

    [download]

    with

      my ($float, $dec) = @_;

    This is almost entirely cosmetic in this context.

I would also point out your algorithm will still be subject to the whims of these small deviations between string and double precision representation. Consider the default case of: 

#!/usr/bin/perl
use strict;
use warnings;

my $number = defined $ARGV[0] ? $ARGV[0] : 1.2549999999999999;
my $places = defined $ARGV[1] ? $ARGV[1] : 2;

printf "%.20f\n", $number; 
print round( $number , $places ), "\n";


sub round {
  my ($float, $decimals) = @_;
  
  my $int_leftShiftFloat = int( $float * 10**($decimals + 1) );
  my $int_Round = int( ( $int_leftShiftFloat + 5 ) / 10 );
  my $float_rightShiftInt = $int_Round / 10**$decimals;
  my $float_Result = $float_rightShiftInt;
  
  return $float_Result
}

[download]
which outputs: 

1.25499999999999990000
1.26

[download]

In reply to Re^4: How to use the int-function? by kennethk
in thread How to use the int-function? by Anonymous Monk

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.