Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I need to know the number of bytes a file would be if I printed a string to a file, before I create the file.

How would one go about doing this?

Replies are listed 'Best First'.
Re: Bytes in a String
by Errto (Vicar) on Jul 03, 2005 at 04:20 UTC
    It depends on the output encoding you intend to use for that file. If the encoding is utf-8, then the anonymous post above is correct, because length will return the number of bytes in UTF-8 when use bytes is in effect. But if your encoding is something else, the result may be different: 
    use strict;
use warnings;
my $x = "abcdefg";
print length $x, "\n";
{
  use bytes;
  print length $x, "\n";
}
open my $fh, ">:encoding(ucs-2)", "out.txt" or die $!;
print $fh $x;
close $fh;
print +(stat "out.txt")[7], "\n"; #print size of file in bytes
__END__
7
7
14

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    A more generic technique for determining the length of a string in a given output encoding: 
    use Encode qw/encode/;
my $x = "abcdefg";
print length(encode("ucs-2", $x)), "\n";

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      CRLF translation may also need to be accounted for.
[reply]
Re: Bytes in a String
by Anonymous Monk on Jul 03, 2005 at 02:34 UTC 
    #!/usr/bin/perl -l

$a = chr(1222) . "abc" . chr(2201);

print length($a);
{
   use bytes;
   print length($a);
}
print length($a);
__END__
5
8
5

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