Error message while reading from file

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

I guess some of you have seen this before...
I read something from an infile in common fashon like this:

while((my $line=<EXP>)=~/\S/)
{
    chomp($line);
    (my ($k), my ($v))=split('=>', $line);
    $k=~s/\s//;
    $v=~s/\s//;
    $experimental_hash{$k}=$v;
}
[download]

The problem is that if I dont have an empty row at the bottom of the infile I get the following error message: "Use of uninitialised value in pattern match (m//) at C:/bla/bla.." This doesn´t cause other trubbles more then that it is irritating. I frequently encounter this problem so I would be happy if you could give me an advice how to get rid of this problem. Thank you

Comment on Error message while reading from file Download Code

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Re: Error message while reading from file by salva (Canon) on Feb 17, 2006 at 11:41 UTC
the problem is that when the loop reachs the EOF, `<EXP>` returns undef. Rewrite the loop as: `while(defined(my $line = <EXP>)) { next unless $line =~/\s/; ... }` [download]	[reply] [d/l] [select]
Re: Error message while reading from file by izut (Chaplain) on Feb 17, 2006 at 11:38 UTC
Just modify your loop. `foreach (<EXP>) { next unless m/\S/; ... }` [download] Igor 'izut' Sutton your code, your rules.	[reply] [d/l]
Re^2: Error message while reading from file by davorg (Chancellor) on Feb 17, 2006 at 11:49 UTC
Why switch from `while` to `foreach`? `while (<EXP>) { next unless /\S/; ... }` [download] -- <http://dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply] [d/l]
Re^2: Error message while reading from file by salva (Canon) on Feb 17, 2006 at 11:46 UTC
generaly, this is not a good idea as it will read the full file in memory and if the file is too big you can run out of RAM.	[reply]
Re: Error message while reading from file by Aristotle (Chancellor) on Feb 20, 2006 at 00:30 UTC
Everyone else gave you a bad transliteration of your loop. The proper rephrasing of that is `while( my $line = <> ) { last unless $line =~ /\S/; # ... }` [download] That is, your loop does not merely skip lines which do not contain non-blanks, it actually terminates as soon as it encounters one. Makeshifts last the longest.	[reply] [d/l]