appending file name

[Anonymous Monk]

Hello

I want to take the file name of a file as input as say abc.csv and separate its name as abc and open a new text file as abc_head.txt (where abc is taken from the input file )

so what I am doing is

    my $filename = <>;
    chomp $filename;  
    my @filenam = split ('\.', $filename);
     my $fi;
     my $fff=($filenam[0],"_header",".txt");
     open($fi,">", $fff) or die "Open failed for $fff: $!";

so what am I doing wrong , because it is not creating abc_header.txt

[kcott]

Take a look at perlop - Comma Operator. [Note that you've created a (hidden) file: .txt]

To concatenate strings, use the join function or the '.' operator (see perlop - Additive Operators).

[marinersk]

Just a note, it wouldn't be hidden on a Windows system simply because it starts with the dot; that's *nix behavior. But you probably knew that. :-)

[hdb]

If you add use warnings; at the beginning of your script, Perl will direct you to the line which you need to change.

[Anonymous Monk]

no I have seen the warning so how can I do it ?

[Anonymous Monk]

Add  use diagnostics; and it will print an explanation of what causes and how to fix the warning from perldiag

[Rahul6990]

Change your code to:


my $filename = "rahul.abc";
    chomp $filename;  
    my @filenam = split ('\.', $filename);
     my $fi;
     my $fff=$filenam[0]."_header".".txt";
    print "\n:$fff:\n"



More on string concatenation

[Skeeve]

For filenames I'd use File::Basename like so:

use File::Basename;
my $filename = <>;
chomp $filename;
my ($name,$path,$suffix) = fileparse($filename, qr/\.[^.]+$/);
print "Path: $path\n";
print "Name: $name\n";
print "Ext : $suffix\n";
my $fff= $path . $name . '_header.txt';

[poj]

Consider using a regular expression,

#!perl
use strict;
my $filename =  'ABcde.cSv';

(my $fff = $filename) =~ s/\.csv$/_header.txt/i;

print "$filename -> $fff\n";

poj

[mtmcc]

Or this:

#!/usr/bin/perl 
use strict;
use warnings;

my $filename = "rahul.abc";
chomp $filename;  

my @filename = split ('\.', $filename);
$filename[$#filename] = 'newEnding.txt';
my $newFilename = join('.', @filename);

print STDERR "OLD: $filename\tNEW: $newFilename\n";

-Michael

[Anonymous Monk]

Hey Michael

the issue is as you posted the code for the previous problem in thread "giving same name to two files " . If the first time input is correct then it works fine , but if the user gives wrong file name , so I am doing this

while (!-e $filename)
     { 
          print "-*-*--*-*--*-*--*-*--*-*--*-*--*-*--*-*--*-*--*-*--*-
+*--*-*--*-*--*-*--*-*--*-*--*-*--*-*-\n";
          print STDERR "\n$filename not found. \n Ensure that you have
+ given the correct file name\n and the file exists in the working dir
+ectory \n.";
          print "Re-enter filename, or q to quit: ";
          $filename = <STDIN>;
          chomp $filename;
         # my @filenam = split ('\.', $filename);
          exit() if $filename eq "q";
     }

the commented line is what I have added , so it takes only the first time name ,not the correct one .

[poj]

By using my @filenam you are declaring it local to the loop and not accessible outside that block. Either move the line to outside and after the while block or remove the my inside the loop.
poj

[marinersk]

Summary of Problem: You are creating a dynamic array instead of contatenating strings.

Simply to get it to run, I adjusted your code as follows:

#!/usr/bin/perl -w

use strict;

my $filename = <>;
chomp $filename;
my @filenam = split ('\.', $filename);
my $fi;
my $fff=($filenam[0],"_header",".txt");
open($fi,">", $fff) or die "Open failed for $fff: $!";

__END__

Which produced the following:

C:\Steve\Dev\PerlMonks\P-2013-07-17@0950-Filename-Transmogrification>p
+erl filenameTransmogrification.pl
Useless use of array element in void context at filenameTransmogrifica
+tion.pl line 9.
Useless use of a constant in void context at filenameTransmogrificatio
+n.pl line 9.
abc.dat

C:\Steve\Dev\PerlMonks\P-2013-07-17@0950-Filename-Transmogrification>d
+ir
 Volume in drive C has no label.
 Volume Serial Number is E88F-F456

 Directory of C:\Steve\Dev\PerlMonks\P-2013-07-17@0950-Filename-Transm
+ogrification

07/17/2013  09:52 AM    <DIR>          .
07/17/2013  09:52 AM    <DIR>          ..
07/17/2013  09:52 AM                 0 .txt
07/17/2013  09:51 AM               232 filenameTransmogrification.pl
               3 File(s)            466 bytes
               2 Dir(s)  78,355,476,480 bytes free

Interestingly, I was expecting it to create 3.txt, but it merely created .txt. I will have to look into why; the clue is in the warning messages, I'm sure.

Anyway, I changed one line:

my $fff=($filenam[0],"_header",".txt");
    to
my $fff=$filenam[0] . "_header" . ".txt";

And got the following results:

C:\Steve\Dev\PerlMonks\P-2013-07-17@0950-Filename-Transmogrification>p
+erl filenameTransmogrification2.pl
abc.dat

C:\Steve\Dev\PerlMonks\P-2013-07-17@0950-Filename-Transmogrification>d
+ir
 Volume in drive C has no label.
 Volume Serial Number is E88F-F456

 Directory of C:\Steve\Dev\PerlMonks\P-2013-07-17@0950-Filename-Transm
+ogrification

07/17/2013  09:53 AM    <DIR>          .
07/17/2013  09:53 AM    <DIR>          ..
07/17/2013  09:52 AM                 0 .txt
07/17/2013  09:53 AM                 0 abc_header.txt
07/17/2013  09:51 AM               232 filenameTransmogrification.pl
07/17/2013  09:52 AM               234 filenameTransmogrification2.pl
               4 File(s)            466 bytes
               2 Dir(s)  78,354,427,904 bytes free

This seems to be closer to what you were trying to accomplish.

So, some observations:

1) Simple string contantenation in Perl is done using the  .  operator.

2) You might benefit from thinking in terms of using reciprocal functions. You used split to break apart the name; it would be prudent to use join to put it back together. split and join are essentially reciprocal functions.

3) There are modules which do a pretty good job of handling most filename related functions, and often honor the rules and trends of the OS you're running on, but this looks like a learn-Perl kind of exercise so there is much to be gained from learning how to do the basic work by hand. Just be aware that modules, especially ones published to CPAN, usually handle a lot of the corner cases you will overlook, so learning to leverage the publicly-shared work of others is a valuable skill in this profession.

Good luck!