Jean, can I email you from know on??? : ) You are so through! Thank you! I now understand the one line code and slurping coding within the array! My reasoning for the array was so that I can only and easily print out specific elements. So do you still suggest just using the while construct instead of the array assuming memory is not an issue?
Derek B. Smith OhioHealth IT UNIX / TSM / EDM Teams Guay Jean-Sébastien <[EMAIL PROTECTED]> 04/02/2004 02:20 PM To: Perl Beginners <[EMAIL PROTECTED]> cc: Subject: RE: using strict Hello Derek, > Guay, Err, my first name is Jean-Sebastien. My last name is Guay. French-language people have a bad habit to put the last name first, as in "Guay, Jean-Sebastien"... So I understand why this is a bit confusing. > What do you mean when you say "Just use $line inside the while, and you'll read one line at a time." ??? > I am doing this, aren't I? No. I will explain step by step what your code does: > open (CRITICALSERVERS, "$crout") || die "can't open file \n: $!"; As I said, you should replace || by or in the above line. See the precedence rules in "perldoc perlop" for details. > while ( defined($line = <CRITICALSERVERS>) ) { Here, you read one line into $line, and the "current line pointer" advances to the next line. The while is essentially there to check that you don't read past the end of file. So in theory, the above construct will read one line at a time, until the end of file. > chomp ($line); Here, you remove the end of line delimiter (\n, \r\n or \r depending on your platform). This is good, before working with the text inside a variable you should make sure there is no end of line. > my @tsm = <CRITICALSERVERS>; Here, you slurp the whole file, minus the first line which you read into $line above, into an array. After this, the whole file will be in your @tsm array, one line per array element, and the "current line pointer" will be at the end of the file. > foreach $_ (@tsm) { > print $_; > } This will print every line that's in the array. Note that as I said above, the first line will not be in the array, so you will not see all the lines of your file printed onscreen... > } > close (CRITICALSERVERS); Perhaps you are not familiar with the term "slurp". What that means, is that you are reading the whole file into memory. This is wasteful, and can lead to problems later, if you try to do it with a very large file (not enough memory, machine starts swapping, etc). But it is also sometimes faster, if you need to do a very simple step on every line of your file. In most cases, you should not slurp a file. Instead, read one line at a time. Here is the code I would suggest. open (CRITICALSERVERS, "$crout") or die "can't open file \n: $!"; my $line; while ( $line = <CRITICALSERVERS> ) { chomp ($line); print $line . "\n"; } close (CRITICALSERVERS); Essentially, the changes are the following: 1) Changed || for or on the open line 2) No need to check if $line is defined after reading, since $line will at least contain a "\n" when the line is empty and will contain nothing at end of file. 3) The while will read one line at a time, and print it. Nowhere do I read the whole file at once, as you did in your "my @tsm = <CRITICALSERVERS>;" line. So that's what I meant. I hope it is all clear. If you really wanted to slurp the file, here is the corresponding code you should use, so that you are not missing one line... open (CRITICALSERVERS, "$crout") or die "can't open file \n: $!"; my @tsm = <CRITICALSERVERS> close (CRITICALSERVERS); foreach my $line (@tsm) { chomp ($line); print $line . "\n"; } As you can see, it is very similar, but since we get the whole file into the array, we can close it right after, and also we loop over the array instead of looping and getting one line at a time until we get to the end of the file. Hope this helps, Jean-Sébastien -----Message d'origine----- De: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Date: 2 avril, 2004 10:12 Ŕ: Guay Jean -Sébastien Cc: Perl Beginners Objet: RE: using strict Guay, ooops..... that would be it! someone's else's eyes are always better! Thanks for the nice explanation! My code is now compiling smoothly! What do you mean when you say " Just use $line inside the while, and you'll read one line at a time." ??? I am doing this, aren't I? FROM GUAY: [[ By the way, why are you reading one line in the whiles parentheses, and then slurping the rest of the file into an array inside the while? ]] RESPONSE FROM DEREK : I did notice this after you pointed it out, so my goal is to read in all the lines and put them in their own element, then print out those specific elements. Do you have any thoughts? thanks! Derek B. Smith OhioHealth IT UNIX / TSM / EDM Teams 614-566-4145 Guay Jean-Sébastien <[EMAIL PROTECTED]> 04/01/2004 05:10 PM To: Perl Beginners <[EMAIL PROTECTED]> cc: Subject: RE: using strict Hello Derek, When using strict, the error message should point you to the line where the error is. It's usually pretty darn good at pointing the right line. In this case, I bet it's this one: > while ( defined($line = <CRITICALSERVERS>) ) { There is no declaration of the $line variable. Try declaring it first, like this: my $line; while ( defined($line = <CRITICALSERVERS>) ) { I think that's the only variable that wasn't declared. If you get any more error messages, you can check them out and figure out what's wrong. Just a suggestion: You should use or instead of || when checking if a file opened correctly, because if you ever want to do some operations on the right side, or will bind less tightly and allow your operations to work correctly without needing parentheses to fix the precedence. By the way, why are you reading one line in the while's parentheses, and and then slurping the rest of the file into an array inside the while? That means your while will only be run once, because at the next iteration you'll already be at the end of the file... Just use $line inside the while, and you'll read one line at a time. You also chomped your line, which is good. Just remember to re-add the line ending ("\n") when printing the lines as you're doing, or else all the lines will be printed on a single, very long line. I'll let the experts explain what soft references and barewords are. I've never used either, as I come from the relatively new school of programming. As I understand, they are features of the language that are dangerous to use in some contexts, so use strict disallows them knowing that if you really want to use them, you'll disable strict for the block of code where you use it, and then re-enable it. Hope this helps, Jean-Sébastien Guay -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] <http://learn.perl.org/> <http://learn.perl.org/first-response> -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] <http://learn.perl.org/> <http://learn.perl.org/first-response>