#!/usr/bin/perl -w
use strict;
my (@eachnum, $binary, $good, $decimal);

print("\n\nEnter a binary number:");
	chomp($binary=<STDIN>);
if ( $binary =~/\D.*/ ) { 
    print("Not a binary number!\n");exit;}
if ( $binary =~/\d.*/ ) { 
    @eachnum = split (//, $binary);
    $good = 1;
	foreach (@eachnum)
	{
	next if /0/ || /1/;
	print("A binary number contains 1's and 0's!\n");
	$good = 0;	
	last;	
	}
    if ( $good == 1 ) {
    convb2d();
    }
} 

sub convb2d {
	$decimal = unpack 
( "N", pack("B32", substr("0" x 32 . $binary, -32 )));
print ("Decimal: $decimal\n");
exit;
}
#eNd