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Today, deMize asked in the chatterbox how to convert the number 4335043554366887798866555766 to hexadecimal. One solution is of course to use dc:

dc -e16o4335043554366887798866555766p

The easiest perl solution is probably to use the Math::BigInt module:

perl -wE 'use Math::BigInt; say Math::BigInt->new("4335043554366887798 +866555766")->as_hex;'

But here's another, more complicated solution.

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; '

Update: deleted the unnecessary sub from the code.

Update 2011-03-18: see also Re: Module for 128-bit integer math? for a list of bigint modules.

Update 2012-08-25: see also Re: Zeckendorf representation for another conversion, this time to a more unusual number system.


In reply to Convert big number from decimal to hexadecimal by ambrus

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