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

Hi, very new to Perl... trying to run: 
#!/usr/bin/perl

open (FILE, 'data.txt');
while (<FILE>) {
chomp;
($name, $email, $phone) = split("\t");
print "Name: $name\n";
print "Email: $email\n";
print "Phone: $phone\n";
print "---------\n";
}
close (FILE);
exit;

[download]
but then I get: readline() on closed filehandle FILE at Readfile1.pl line 4 why is that? what's wrong? 10x, Tuval

Replies are listed 'Best First'.
Re: can't open a file?
by Bloodnok (Vicar) on Oct 01, 2009 at 22:40 UTC
    It's not unlike the call to open failed, but your script failed to notice and act accordingly e.g. by dieing.

    Try, at line 2, inserting 

    use warnings;
use strict;
use autodie;

    [download]
    . These 3 lines will have the effect of
    • giving you a heads-up on any potential problems,
    • telling you of any scripting errors and finally,
    • causing the script to die with an explanation if a system call e.g. the aforementioned open(), fails for any reason.

    A user level that continues to overstate my experience :-))
[reply]
[d/l]
[select]
Re: can't open a file?
by Anonymous Monk on Oct 01, 2009 at 22:35 UTC
    You're not doing any error checking. perldoc -f open 
      open(my $fh, '<', "input.txt") or die $!;

and for writing:

  open(my $fh, '>', "output.txt") or die $!;

    [download]
    Or 
    use autodie;
[reply]
[d/l]
Re: can't open a file?
by ikegami (Patriarch) on Oct 02, 2009 at 04:33 UTC

    Quick tip: split's first arg is a regex pattern. It doesn't match the string literally. Use a match operator instead of a string, and you'll avoid future confusion. 

    my ($name, $email, $phone) = split(/\t/);

    [download]

    I also noticed your script lacks use strict; use wanrings;. Please use them. Not using them hides errors. This one's important.

[reply]
[d/l]
[select]
Re: can't open a file?
by leocharre (Priest) on Oct 02, 2009 at 15:57 UTC
    This note is to echo what ikegami said- This is one of the most important things you have to do as you learn perl.. 'use strict;' - use that. Just believe..

    Here's your script rewritten with strict.. (untested) 

    #!/usr/bin/perl
use strict;


open (FILE, 'data.txt');
while (<FILE>) {
   chomp;
   my ($name, $email, $phone) = split(/\s/); # split on whitespace
   print "Name: $name\n";
   print "Email: $email\n";
   print "Phone: $phone\n";
   print "---------\n";
}
close (FILE);
exit;

    [download]
[reply]
[d/l]

Back to Seekers of Perl Wisdom