[SOLVED] Perl problems

jfsiegel · 05-04-2012, 02:04 PM

Hello,
I had posted a short time ago about a problem I was having trying to sort through a file via awk over in the Solaris forum but while the solution worked I am trying to see if I can handle the same issue as a Perl program. What I am trying to do is to get a repeatable program that can target the 10th and 11th column of data and extract it from one file and place it into a new file. There will not always be an 11th column. I would like to get the results from each line of the input file concatonated onto the end of the previous line ignoring any newlines. The ability to designate files for input and output is relevant because I want to be able to reuse the same program several times in a row on several different files.

Code:

#!/usr/bin/perl -w
print "Input File Name: ";
$input = <>;
print "Output File Name: ";
$parse = <>;

open ($input, "$input");
open ($parse, "$parse");
while (<$input>) {
    split (/ /);
    print $parse "$column[10],column[11]\n";
    }
close ($input);
close ($parse);

What I have been getting when I try to run this is an error for each line of the input file that reads as follows:

Code:

use of uninitialized value in concatenation (.) or string at ./script.pl line 11, <input_file.txt> line 1.
use of uninitialized value in concatenation (.) or string at ./script.pl line 11, <input_file.txt> line 1.
Filehandle output.pl opened only for input at ./script.pl line 11, <input_file.txt> line 1.

I am really trying to figure this out in Perl terms and I am learning on the fly. Thanks for your assistance in advance.

markush · 05-04-2012, 05:16 PM

Hi, I think you mean this:

Code:

#!/usr/bin/perl 

use strict ;
use warnings ;

print "Input File Name: ";
my $input = <>;
print "Output File Name: ";
my $parse = <>;

open (INPUT, $input);
open (PARSE, ">$parse"); # don't forget to open for writing
my @column ;  # don't forget to initialize @column
while (<INPUT>) {
     @column = split (/ /);
     print PARSE "$column[1],$column[2]\n"; # I didn't have a file with that much columns ;)
}
close (INPUT);
close (PARSE);

Markus

Sergei Steshenko · 05-04-2012, 05:44 PM

Quote:

Originally Posted by markush

Hi, I think you mean this:

Code:

#!/usr/bin/perl 

use strict ;
use warnings ;

print "Input File Name: ";
my $input = <>;
print "Output File Name: ";
my $parse = <>;

open (INPUT, $input);
open (PARSE, ">$parse"); # don't forget to open for writing
my @column ;  # don't forget to initialize @column
while (<INPUT>) {
     @column = split (/ /);
     print PARSE "$column[1],$column[2]\n"; # I didn't have a file with that much columns ;)
}
close (INPUT);
close (PARSE);

Markus

And "INPUT" and "PARSE" are global - for now good reason.

You can write

Code:

open(my $ifh, $input) or die "cannot open '$input' file for reading: $!";

.

jfsiegel · 05-07-2012, 09:00 AM

Thanks that almost got it. I had to add a Chomp statement to get the output I was looking for:

Code:

while (<INPUT>) }
     chomp;
     @column = split (/ /);
     print PARSE "$column[11]$column[12]";
}

Also I noted one thing...I received a great number of errors that read:

Code:

Use of unititialized value in concatenation (.) or string at ./Script line 17, <INPUT> line #####.

Mind you when I look at the output it is all there. What I think is happening is that there are only certain lines where I have a Column 12...but i needed to capture them nevertheless. I am wondering if there is a way to tell the program to print any colums at or past a designated number so that it can find them automatically without a screen full of what appear to be errors. Thanks!

Sergei Steshenko · 05-07-2012, 10:22 AM

Quote:

Originally Posted by jfsiegel

Thanks that almost got it. I had to add a Chomp statement to get the output I was looking for:

Code:

while (<INPUT>) }
     chomp;
     @column = split (/ /);
     print PARSE "$column[11]$column[12]";
}

Also I noted one thing...I received a great number of errors that read:

Code:

Use of unititialized value in concatenation (.) or string at ./Script line 17, <INPUT> line #####.

Mind you when I look at the output it is all there. What I think is happening is that there are only certain lines where I have a Column 12...but i needed to capture them nevertheless. I am wondering if there is a way to tell the program to print any colums at or past a designated number so that it can find them automatically without a screen full of what appear to be errors. Thanks!

You have those warnings because your code tries to access array elements which do bot exist.

Rather than asking here first learn. For example, read about all built-in Perl functions: http://perldoc.perl.org/index-functions.html - look for 'exists', 'defined'.

Look for 'scalar' in http://perldoc.perl.org/perldata.html .