First a remark: 1110 1111 is not a hexadecimal number, it is in binary and it is not even the binary representation of 254, which is 11111110 (254 is even, so its rightmost bit cannot be 1).

Taking that into account, the following will do what you want: 

use strict;

my $debug = 1;
my $dec= 254;
print "$dec\n";
print shift_left($dec) ;

sub dec2bin {
    my $str = unpack("B32", pack("N", shift));
    $str =~ s/^0+(?=\d)//;   # otherwise you'll get leading zeros
    print "$str\n" if $debug;
    return $str;
}

sub bin2dec {
    return unpack("N", pack("B32", substr("0" x 32 . shift, -32)));
}

sub shift_left {
    my $bin_reversed = reverse dec2bin(shift);
    chop $bin_reversed;
    print ' ' . reverse ($bin_reversed) . '0' . "\n" if $debug;
    return bin2dec(reverse ($bin_reversed) . '0');
}

[download]
Output: 
254
11111110
 11111100
252

[download]
The bin2dec and dec2bin routines are from the Perl Cookbook (recipe 2.4).

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

In reply to Re: Decimal to Hexadecimal conversion and extraction MSB by CountZero
in thread Decimal to Hexadecimal conversion and extraction MSB 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.