opening files

harry34 has asked for the wisdom of the Perl Monks concerning the following question:

I have a lots of .txt files containing numerical data.
The following code opens a program called platon and it in turn opens a single .txt file and does various things with it.

($in_filename, $out_filename) = @ARGV;
$out_filename = $in_filename if ( !($out_filename) ); 
$ins_filename = "$in_filename.txt";          
system ("platon -c $txt_filename");
[download]

How would I change this code so it opens all my .txt files one after another (they are numbered sequentially).
cheers harry

Comment on opening files Download Code

Replies are listed 'Best First'.
Re: opening files by Aristotle (Chancellor) on Jul 08, 2002 at 13:50 UTC
Why do you append the `.txt` extension to `$ins_filename` but use `$txt_filename` in your `system`? Anyway: `($in_filename, $out_filename) = @ARGV; $out_filename = $in_filename if ( !($out_filename) ); for my $num (1..20) { system ("platon", "-c", "$in_filename$num.txt") +}` [download] Note it's much better to use the multi-argument form of `system`. See perldoc -f system. Makeshifts last the longest.	[reply] [d/l]
Re: opening files by jjohn (Beadle) on Jul 08, 2002 at 15:03 UTC
How would I change this code so it opens all my .txt files one after another (they are numbered sequentially). In a Bourne-like command shell (like bash), you could do: `for i in txt; do platon -c $i; done` [download] In Perl on a Unix box (or a shell that expands the command line arguments for you), this should work: `for my $infile (@ARGV){ next unless -e $infile; system("platon -c $infile"); }` [download] This program expects to be passed the whole list of files to process, like this (assuming this code above is in a file called 'batch.pl'): `$ perl batch.pl .txt` [download] The -e file test operator attempts to make sure that the argument to be processed is an existing file. This is a small attempt to prevent a rogue user from abusing your script. In your environment security may not be an issue, but this sanity check is easy to do. I don't understand how the $out_filename argument is used in your code, so I've silently ignored it (well, not so silently, I guess :-) If I were on a Unix system, I'd opt for the small bit of shell script magic to drive your platon program. Of course, I may not be understanding some of your requirements (i.e. do the source files need to be executed in a particular order? Must existing outfiles not be overwritten?, etc). Of course, Perl is great for bring a Unix-like environment to a non-Unix OS. I've done a bit of Perl scripting on NT boxes and Perl has really saved me a lot of MSDOS batch language pain. Hope this helps.	[reply] [d/l] [select]