Substituting data

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

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Re: Substituting data by kvale (Monsignor) on Jun 28, 2002 at 17:48 UTC
The problem is that you are mixing up regex elements with straight text. Try: `$line =~ s/\t/ /g; $line = "\a" . $line; # simplest # $line =~ s/^/\a/; # alternative using s///` [download] -Mark	[reply] [d/l]
Re: Substituting data by bronto (Priest) on Jun 28, 2002 at 21:17 UTC
Tons of confusion over there, eh? `:-)` First of all: you are opening your database and slurping in at once in memory. It's ok if it's not too big, but in case it is and you have enough disk space I suggest you to read line by line and write to another file. If you want, you could end your script by overwriting the old file with the newly created one; check File::Copy and it's function `move` for details. Second: You use double quotes around `$db` in your `open`s: that would be needed if you specify, for example, `"> $db"` to mean overwrite the file. In your situation double quotes are useless. Next: your foreach cycle doesn't print on `DATA`, which would be then left empty! And finally: you used a character class `\s` where it had no meaning in the first substitution, and you swapped the matching string with the substitute in the second. A slightly revised (but untested!) version of your code could be: `use strict ; # now and forever! my $db = 'aaa.txt'; open DATA, "< $db" or die "did not open for reading: $!\n"; my @dat = <DATA> ; # don't need parentheses, context forced by @dat close DATA; open DATA, "> $db" or die "did not open for writing: $!\n"; foreach my $line (@dat) { # Indent, it's useful! $line =~ s/main/index/g; $line =~ s/\t/ /g; #This is not working $line =~ s/^/\a/g; #This is not working print DATA $line; } close DATA ;` [download] Ciao! `--bronto` # Another Perl edition of a song: # The End, by The Beatles END { $you->take($love) eq $you->made($love) ; }	[reply] [d/l] [select]
Re: Substituting data by mikeirw (Pilgrim) on Jun 28, 2002 at 17:46 UTC
Try this: `$line =~ s/\t/ /g; $line =~ s/^/\a/;` [download]	[reply] [d/l]
Re: Re: Substituting data by Anonymous Monk on Jun 28, 2002 at 18:04 UTC
Thanks for the answers to my script problem.	[reply]
Re: Substituting data by fruiture (Curate) on Jun 28, 2002 at 18:35 UTC
you seem to have mixed up the order of s/PATTERN/RELACEMENT/ but that was already told you. I just cannot stop myself from trying to give good advice ... Have a look at perlfaq4 'What's wrong with always quoting "$vars"'. I also wonder why you open the same file twice and why you do not iterate via while(<HANDLE>) which would save the memory consumed by the array @dat .	[reply]
Re: Substituting data by robobunny (Friar) on Jun 28, 2002 at 17:53 UTC
as kvale said, unless you actually want a literal \a at the beginning, then do: `$line =~ s/^/\\a/;` [download] i don't see why you'd want either one of them there, so i don't know which one you want.	[reply] [d/l]
Re: Substituting data by flounder99 (Friar) on Jun 28, 2002 at 19:09 UTC
Aside from your regexes you will want to add a `>` to your second open or you will not be able to write to the file. For example: `open (FILE, ">blah.txt") or die; print (FILE "1 blah\n2 blah\n3 blah\n") or warn "could not print"; close FILE; open (FILE, "blah.txt") or die; # NOTE: no > print (FILE "new data\n") or warn "could not print"; close FILE; open (FILE, "<blah.txt") or die; print <FILE>, "\n"; close FILE; __OUTPUT__ could not print at temp.pl line 5. 1 blah 2 blah 3 blah` [download] -- flounder	[reply] [d/l] [select]