perl

I first asked /sci/ but now I'm on the right board. I'm having some issues with a program I'm writing in perl.
The program starts with the string "9" and mod's it by a prime.
If the result is > 0 then it concatenates another 9 to the string and continues until the result is equal to 0.
It works fine until the number has 16 digits: 9999999999999999 % 17 = 1 for example. It appears the result after mod is always 1 higher than it should be when the number has more than 15 digits, regardless of the prime used.

I tried using bigint/bignum libraries but to no avail. Any ideas?

Thanks in advance.

Don't do it with a string, silly! Do it with a number.

Why would that cause a problem only after the length has reached 16?

I've just tried typecasting before doing the operation; as I expected, it didn't work (perl automatically decides what data type upon doing the operation)

print "99999999999999999" % 17 . "\n";
use bignum;
print "99999999999999999" % 17 . "\n";
10
9

I've already tried using bignum/bigint

>>6
the result after mod is always 1 higher than it should be
10
9

use bignum

>>7
use MY ANUS;

If I'm getting the primes out of a file, would that affect it? I tried using chomp. bignum doesn't work.

>>9
I'm not sure you understand. Bignum does work.
Don't blame your inadequacies on your tools.

>>9
Look, the guys here are going to be dicks to you without explaining why until you post your source (use code tags!)

Perl is known for being just a hair more batshit insane when it comes to numbers than you would expect. That said, bignum should work... and if it doesn't then it's probably something you implied while DWIMing something