Re: reading file into an array

for(my $x=14; $x<@fileContents; $x++)
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Array indexes in Perl begin with zero, so that's actually going to start at line 15.

Also, a more perlish way of initiating that loop would be:

for (13 .. $#fileContents) {
    print "$fileContents[$_]\n";    # Or whatever
}
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However, a much better way to process a file line by line is with a while loop. Something like this:

my $lines_to_skip = 14;

while (my $line = <$file>) {
    # $. will give you the current line number of the file
    next if ($. <= $lines_to_skip);  
    chomp($line);
    # Do stuff with $line
}
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Hope this helps,
Darren :)

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Re^2: reading file into an array by johngg (Canon) on Dec 05, 2008 at 22:16 UTC
Processing line by line in a while loop is a a more scaleable solution but I would prefer to separate the line skipping part from the main line processing logic. I think it keeps things clearer but others may disagree. `my $linesToSkip = 14; my $discard = <$file> for 1 .. $linesToSkip; while( my $line = <$file> ) { chomp $line; ... }` [download] Calling the scalar `$discard` makes it clear that it is something we are not interested in whereas `$line` might be something we want to work with. I hope you find these thoughts of interest. Cheers, JohnGG	[reply] [d/l] [select]
Re^2: reading file into an array by JadeNB (Chaplain) on Dec 05, 2008 at 23:59 UTC
I can't help mentioning, because I was so happy when I stumbled across it, the following cute syntax for skipping a constant number of lines using the range operator: `while ( my $line = <$file> ) { next if 1 .. 14; do_stuff; }` [download] (Unfortunately, it doesn't work with a variable—for example, `next if 1 .. $lines_to_skip`—since the range operator just tests whether `$lines_to_skip` is a true value, not whether it's equal to `$.`.)	[reply] [d/l] [select]
Re^2: reading file into an array by vassago (Novice) on Dec 05, 2008 at 21:26 UTC
Sorry, it starts on line 15. Thanks for the reply. It is working now. And I like your way of the while loop much better than what I used. However, I'm new to perl and don't fully understand your for loop. I assume the "13 .." just means start at 14 but why is there a '#' in front of the fileContents and why $ instead of @? Java was my first language so perl is very different and its taking a lot of getting used to. Thanks for the replies!	[reply]
Re^3: reading file into an array by McDarren (Abbot) on Dec 05, 2008 at 21:52 UTC
$# (not #$) refers to the index of the last element of an array. The "at-sign" sigil (@) is used when you refer to two or more elements of an array. If you are accessing (or referring to) a single element of an array, then the "dollar-sign" ($) sigil is used. For example: `my @foo = qw/a b c/; print "$foo[1]\n"; # Prints b print "@foo\n"; # Prints a b c print "$foo[$#foo]\n"; # Prints c (but you would probably never do th +is) print "$foo[-1]\n"; # Also prints c (a better way than the previou +s) print "@foo[0,2]\n"; # Prints a c` [download] Cheers, Darren :)	[reply] [d/l]
Re^3: reading file into an array by gwadej (Chaplain) on Dec 05, 2008 at 21:41 UTC
For an array `@array`, `$#array` gives the index of the last item in the array. It's a minor piece of cryptic Perl syntax. G. Wade	[reply] [d/l] [select]