Question

I want to write a perl script to parse text files with a lot of 64-bit integers in it. All integers are written in hex.

I need to

• Read hexes from input
• Compare 64-bit ints (<, =, >)
• Subtract 64-bit ints
• Output 64-bit hexes

I need to use 32-bit perl and I can’t use any CPAN/external module (the script must be portable).

PS my perl is 5.8 (and this is minimal version which will be used for the script)

PPS bignum/ bigint errors:

$ perl -e 'use bignum; $_=hex("0x0000123412345678")'
Integer overflow in hexadecimal number at -e line 1.

$ perl -e 'use bigint; $_=hex("0x0000123412345678")'
Integer overflow in hexadecimal number at -e line 1.

PPPS: no from_hex here.

$ perl -e 'use Math::BigInt; $_=Math::BigInt->from_hex("0x0000123412345678");'
Can't locate object method "from_hex" via package "Math::BigInt" at -e line 1.

And no qw/hex/:

$ perl -e 'use bigint qw/hex/; $_=hex("0x0000123412345678")'
unknown option hex at /usr/lib/perl5/5.8/bigint.pm line...

PPPPS: but new() works:

$ perl -e 'use Math::BigInt; $_=Math::BigInt->new("0x0000123412345678"); print  $_->as_hex(),"\n";'
0x123412345678

Answer 1

The core pragma bigint will let you transparently work with integers larger than your system can support. There are associated functions in the Math::BigInt core library to convert from and to a hex representation.