[Perl-beginners] String length limits?

Hi Chris,

Perl has no string length limit. You are only limited by the amount of
memory that is available.

If your program is misbehaving then I fear it is the programs error (or well
the person that wrote it ;-) rather then perl or any limit on the length of
a string.

On an average machine these days I would say you can store the equivalent of
all the characters in a small library in your string before you start
running out of memory. So I would not worry about 200 pieces of data. The
last time I ran into a memory problem I was working with several sets of a
few million strings stored in hashes and arrays that I was mixing and
matching in a well not very elegant way (emergency solution needed to work
now rather then in 5 minutes, at least that is my story and I'm sticking to
it)... a few hundred even when they are very long should not cause an issue
at all.

Regards,

Rob

Hi!
And as for the current implementation, i think it's 2 or 4 GB (uint/sint
index into string length?).

But basically, if you have a single scalar of that size, the perl
interpreters limits should be the least of your problems. If you're
going this way, please redesign (a single, accidental copy of a string
has the potential to bring the system to a standstill).

But a few megabytes won't be any problem...
...until you do something unwise like split// and turn you scalar into a
multi-million elements array.

LG
Rene

I have a file of 1s and 0's that is 15689303 bytes;

running the program below takes about 10 seconds on reasonably fast dual
core with 4 GByte of RAM

===============================================================

#!/usr/bin/perl

use strict;
use warnings;

my $rng = "/home/owen/rng_formatted";
open (my $RNG, "<", "$rng") or die "$!\n";
while (<$RNG>) {
my @bits = split //;
my $nr_bits = @bits;
print "Number of bits in the file is $nr_bits\n";
}

===============================================================
owen@owen-desktop:~/P/Perlscripts$ perl beg1.pl
Number of bits in the file is 15689303

Not the best way to get the file size :-)



Owen

All files on a binary computer are composed of 1s and 0s. :-)

Why are you copying $rng to a string?

perldoc -q quoting

If you want a bit count then that should be:

my $nr_bits = 8 * @bits;

Although you don't need to create an array to count bytes:

my $nr_bytes = tr///c;

If you want the size of a file just use the -s operator:

print "Number of bytes in the file is ", -s $rng, "\n";

So there are no newlines in your file?



John

Hi,

Chris Coggins <cacoggins@cox.net> asked:
In Perl, string size is limited to the amount of memory available to your process, which may be less than the amount of memory installed in your computer.

Care to elaborate on "weird behavior" for us?

Could it be a file systems problem, i.e. writing more than 4GB to a single file on a FAT32 filesystem?

Does the weirdness happen in the context of a web application? If yes, could it be a file locking issue?

If it's none of the above, did you run a memtest yet?

HTH,
Thomas