Re: opening many files

Sure, you can open them in a loop. You could put your file descriptors in an array, and then loop through them as you print each line. As long as your system will let a process have that many open files, something like this should work (untested). It's not at all flexible, but since you seem to know that all your files have the same number of lines and the same format, it doesn't need to be. Also, if you use a CSV module, you may want to make an array of object references rather than simple file descriptors, but the looping concept would be the same.

my @fds;
for (1..200){
  open my $fds[$_], '<', "datafile$_" or die $!;
}

for my $ln (1..948){
  print "$ln has ";
  for my $fdn (1..200){
    my $line = <$fds[$fdn]>;
    my $field3 = get_third_field_using_whatever_csv_method($line);
    print $field3;
    print ' ' unless $fdn == 200;
  }
  print "\n";
}
[download]

Aaron B.
My Woefully Neglected Blog, where I occasionally mention Perl.

Comment on Re: opening many files Download Code

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Re^2: opening many files by jwkrahn (Abbot) on Feb 26, 2012 at 23:23 UTC
`open my $fds[$_], '<', "datafile$_" or die $!;` [download] You can't use my on an array element. `my $line = <$fds[$fdn]>;` [download] From I/O Operators: If what's within the angle brackets is neither a filehandle nor a simple scalar variable containing a filehandle name, typeglob, or typeglob reference, it is interpreted as a filename pattern to be globbed, and either a list of filenames or the next filename in the list is returned, depending on context. This distinction is determined on syntactic grounds alone. That means "<$x>" is always a readline() from an indirect handle, but "<$hash{key}>" is always a glob(). That's because $x is a simple scalar variable, but $hash{key} is not--it's a hash element. Even "<$x >" (note the extra space) is treated as "glob("$x ")", not "readline($x)".	[reply] [d/l] [select]
Re^3: opening many files by aaron_baugher (Curate) on Feb 27, 2012 at 01:18 UTC
Well, I did say it was untested, but that's a poor excuse. ++ for the correction; my 'my' should be removed on that line. Aaron B. My Woefully Neglected Blog, where I occasionally mention Perl.	[reply]