CUFP
ambrus
<p>
Today, [deMize] asked in the chatterbox how to convert the number 4335043554366887798866555766 to hexadecimal. One solution is of course to use dc:
<c>
dc -e16o4335043554366887798866555766p
</c>
<p>
The easiest perl solution is probably to use the Math::BigInt module:
<c>
perl -wE 'use Math::BigInt; say Math::BigInt->new("4335043554366887798866555766")->as_hex;'
</c>
<p>
But here's another, more complicated solution.
<c>
perl -wE '
sub hadd {
no warnings "uninitialized";
my($a, $b) = @_; my @b = @$b; my $c;
for (my $k = 0; @b || $c; $k++) {
$c = 16 <= ($$a[$k] += $c + shift @b); $$a[$k] %= 16;
}
}
my $n = "4335043554366887798866555766";
my $h = []; for my $d (split //, $n) {
hadd $h, $h; hadd my $g = [], $h; hadd $h, $_ for $h, $h, $g, [$d];
}
say join "", reverse map { sprintf "%x", $_; } @$h;
'
</c>
<p>
<b>Update:</b> deleted the unnecessary sub from the code.
<!-- kw: bigint arithmetic engine, big integer, alu, long addition, number base conversion, radix conversion, arithmetic engine, fingers and toes, classical algorithms -->
<p>
<b>Update 2011-03-18:</b> see also [id://886513] for a list of bigint modules.
<p>
<b>Update 2012-08-25:</b> see also [id://989716] for another conversion, this time to a more unusual number system.