Re: Opening a file, editing, copying to another

Your files are empty becuase you are printing nothing to them.

In your loop you have

$commentout = $commentout .= $position;
s/$position/$commentout/;
print OTHER;  #THIS LINE HERE!!
$x++;
[download]

That line does nothing. If you want to write to your file you would do

print OTHER "I am printing foo to file\n";
[download]

another thing that should be pointed out

s/$position/$commentout/
[download]

This does nothing. Are you trying to do a regular expresion with that? If so you need to go back and read up on the Perl regular expressions. It should have the form

$variable =~ s/<regular-expression>/<substitution-here>/;

#For example the following 

my $variable = "Blue Car";
print $variable."\n";
$variable =~ s/Blue/Red/;
print $variable."\n";
[download]

I hope that helps

p.s. For better posting encapsulate your scripts inside the

<code>

tags.

Comment on Re: Opening a file, editing, copying to another Select or Download Code

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Re^2: Opening a file, editing, copying to another by GrandFather (Saint) on Jun 20, 2007 at 23:30 UTC
That line does nothing. If you want to write to your file you would do Actually, no. Consider: `$_ = "HW"; s/HW/Hello World/; print STDOUT;` [download] Prints: `Hello World` [download] You perhaps need to learn about $_? See $ARG/$_ in perlvar. DWIM is Perl's answer to Gödel	[reply] [d/l] [select]
Re^3: Opening a file, editing, copying to another by toolic (Bishop) on Jun 20, 2007 at 23:37 UTC
Just to be extremely explict, "print STDOUT;" is the same as "print STDOUT $_;". Both of these statements print the value of the special Perl variable, $_, to STDOUT. Similarly, "print OTHER;", which is the same as "print OTHER $_;", prints the value of $_ to the "OTHER" file.	[reply]
Re^4: Opening a file, editing, copying to another by GrandFather (Saint) on Jun 20, 2007 at 23:44 UTC
Actually `print;` [download] suffices. STDOUT is assumed if no file handle is provided. However I used `print STDOUT;` in the sample code to maintain consistency with the OP's sample code. The important thing for Grundle is to be aware of `$_` and where it is used as the default. DWIM is Perl's answer to Gödel	[reply] [d/l] [select]
Re^3: Opening a file, editing, copying to another by Grundle (Scribe) on Jun 21, 2007 at 13:57 UTC
Ahh ++ I wasn't aware of that. That seems to be a sloppy way of doing things in my mind, even though it is a quicker shorthand. In any case I do not see where `$_` is ever being set. Running the code myself it comes up empty for every iteration. The data that he wants to operate on is stored in his 2-D Array `$list[][]`. It makes complete sense that nothing is sent to his files because `$_` is empty. Thanks for pointing out my mistake ;) Although I know about `$_` I rarely use it. I find it more readable to explicitely name my variables, and it aids in maintainability for future changes.	[reply] [d/l] [select]
Re^4: Opening a file, editing, copying to another by GrandFather (Saint) on Jun 21, 2007 at 14:25 UTC
You have to know about and use $_ if you use map, grep or for (as a statement modifier) and for various common Perl idioms. If you are not using map, grep or statement modifiers then you are missing out on some major workhorses in Perl. In the op's situation I agree that using a variable is likely to make the intent clearer, but there are a multitude of problems with the code apart from that. DWIM is Perl's answer to Gödel	[reply]